Microelectronic assemblies

ABSTRACT

Microelectronic assemblies, and related devices and methods, are disclosed herein. For example, in some embodiments, a microelectronic assembly may include a package substrate including a dielectric material having a first surface and an opposing second surface, a first photodefinable material on at least a portion of the second surface, and a second photodefinable material on at least a portion of the first photodefinable material, wherein the second photodefinable material has a different material composition than the first photodefinable material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage application under 35 U.S.C. § 371of PCT International Application Serial No. PCT/US2017/068912, filed onDec. 29, 2017 and entitled “MICROELECTRONIC ASSEMBLIES,” which is herebyincorporated by reference herein in its entirety.

BACKGROUND

Integrated circuit dies are conventionally coupled to a packagesubstrate for mechanical stability and to facilitate connection to othercomponents, such as circuit boards. The interconnect pitch achievable byconventional substrates is constrained by manufacturing, materials, andthermal considerations, among others.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example, not by way oflimitation, in the figures of the accompanying drawings.

FIG. 1 is a side, cross-sectional view of an example microelectronicassembly, in accordance with various embodiments.

FIG. 2 is a bottom view of a die included in the microelectronicassembly of FIG. 1, in accordance with various embodiments.

FIGS. 3-11 are side, cross-sectional views of example microelectronicassemblies, in accordance with various embodiments.

FIGS. 12-16 are top views of example arrangements of multiple dies in amicroelectronic assembly, in accordance with various embodiments.

FIGS. 17A-17F are side, cross-sectional views of various stages in anexample process for manufacturing the microelectronic assembly of FIG.5, in accordance with various embodiments.

FIGS. 18A-18B are side, cross-sectional views of various stages inanother example process for manufacturing the microelectronic assemblyof FIG. 5, in accordance with various embodiments.

FIGS. 19A-19H are side, cross-sectional views of various stages inanother example process for manufacturing the microelectronic assemblyof FIG. 5, in accordance with various embodiments.

FIG. 20 is a side, cross-sectional view of an example microelectronicassembly, in accordance with various embodiments.

FIGS. 21A-21B are side, cross-sectional views of various stages in anexample process for manufacturing the microelectronic assembly of FIG.20, in accordance with various embodiments.

FIGS. 22-25 are side, cross-sectional views of package substrates thatmay be included in a microelectronic assembly, in accordance withvarious embodiments.

FIG. 26 is a top view of a recess in a package substrate, in accordancewith various embodiments.

FIGS. 27A-27E are side, cross-sectional views of various stages in anexample process for manufacturing the package substrate of FIG. 22, inaccordance with various embodiments.

FIGS. 28A-28B are side, cross-sectional views of a package substratethat may be included in a microelectronic assembly, in accordance withvarious embodiments.

FIGS. 29A-29D are side, cross-sectional views of various stages in anexample process for manufacturing the package substrate of FIG. 28, inaccordance with various embodiments.

FIG. 30 is a side, cross-sectional view of an example microelectronicassembly, in accordance with various embodiments.

FIG. 31 is a top view of a wafer and dies that may be included in amicroelectronic assembly, in accordance with any of the embodimentsdisclosed herein.

FIG. 32 is a side, cross-sectional view of an integrated circuit (IC)device that may be included in a microelectronic assembly, in accordancewith any of the embodiments disclosed herein.

FIG. 33 is a side, cross-sectional view of an IC device assembly thatmay include a microelectronic assembly, in accordance with any of theembodiments disclosed herein.

FIG. 34 is a block diagram of an example electrical device that mayinclude a microelectronic assembly, in accordance with any of theembodiments disclosed herein.

DETAILED DESCRIPTION

Microelectronic assemblies, and related devices and methods, aredisclosed herein. For example, in some embodiments, a microelectronicassembly may include a package substrate including a dielectric materialhaving a first surface and an opposing second surface, a firstphotodefinable material on at least a portion of the second surface, anda second photodefinable material on at least a portion of the firstphotodefinable material, wherein the second photodefinable material hasa different material composition than the first photodefinable material.

Communicating large numbers of signals between two or more dies in amulti-die integrated circuit (IC) package is challenging due to theincreasingly small size of such dies, thermal constraints, and powerdelivery constraints, among others. Various ones of the embodimentsdisclosed herein may help achieve reliable attachment of multiple ICdies at a lower cost, with improved power efficiency, with higherbandwidth, and/or with greater design flexibility, relative toconventional approaches. Various ones of the microelectronic assembliesdisclosed herein may exhibit better power delivery and signal speedwhile reducing the size of the package relative to conventionalapproaches. The microelectronic assemblies disclosed herein may beparticularly advantageous for small and low-profile applications incomputers, tablets, industrial robots, and consumer electronics (e.g.,wearable devices).

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof wherein like numeralsdesignate like parts throughout, and in which is shown, by way ofillustration, embodiments that may be practiced. It is to be understoodthat other embodiments may be utilized, and structural or logicalchanges may be made, without departing from the scope of the presentdisclosure. Therefore, the following detailed description is not to betaken in a limiting sense.

Various operations may be described as multiple discrete actions oroperations in turn, in a manner that is most helpful in understandingthe claimed subject matter. However, the order of description should notbe construed as to imply that these operations are necessarily orderdependent. In particular, these operations may not be performed in theorder of presentation. Operations described may be performed in adifferent order from the described embodiment. Various additionaloperations may be performed, and/or described operations may be omittedin additional embodiments.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B, and C). The drawings are not necessarilyto scale. Although many of the drawings illustrate rectilinearstructures with flat walls and right-angle corners, this is simply forease of illustration, and actual devices made using these techniqueswill exhibit rounded corners, surface roughness, and other features.

The description uses the phrases “in an embodiment” or “in embodiments,”which may each refer to one or more of the same or differentembodiments. Furthermore, the terms “comprising,” “including,” “having,”and the like, as used with respect to embodiments of the presentdisclosure, are synonymous. As used herein, a “package” and an “ICpackage” are synonymous, as are a “die” and an “IC die.” The terms “top”and “bottom” may be used herein to explain various features of thedrawings, but these terms are simply for ease of discussion, and do notimply a desired or required orientation. As used herein, the term“insulating” means “electrically insulating,” unless otherwisespecified.

When used to describe a range of dimensions, the phrase “between X andY” represents a range that includes X and Y. For convenience, the phrase“FIG. 17” may be used to refer to the collection of drawings of FIGS.17A-17F, the phrase “FIG. 18” may be used to refer to the collection ofdrawings of FIGS. 18A-18B, etc. Although certain elements may bereferred to in the singular herein, such elements may include multiplesub-elements. For example, “an insulating material” may include one ormore insulating materials. As used herein, a “conductive contact” mayrefer to a portion of conductive material (e.g., metal) serving as anelectrical interface between different components; conductive contactsmay be recessed in, flush with, or extending away from a surface of acomponent, and may take any suitable form (e.g., a conductive pad orsocket, or portion of a conductive line or via).

FIG. 1 is a side, cross-sectional view of a microelectronic assembly100, in accordance with various embodiments. A number of elements areillustrated in FIG. 1 as included in the microelectronic assembly 100,but a number of these elements may not be present in a microelectronicassembly 100. For example, in various embodiments, the heat spreader131, the thermal interface material 129, the mold material 127, the die114-3, the die 114-4, the second-level interconnects 137, and/or thecircuit board 133 may not be included. Further, FIG. 1 illustrates anumber of elements that are omitted from subsequent drawings for ease ofillustration, but may be included in any of the microelectronicassemblies 100 disclosed herein. Examples of such elements include theheat spreader 131, the thermal interface material 129, the mold material127, the second-level interconnects 137, and/or the circuit board 133.Many of the elements of the microelectronic assembly 100 of FIG. 1 areincluded in other ones of the accompanying figures; the discussion ofthese elements is not repeated when discussing these figures, and any ofthese elements may take any of the forms disclosed herein. In someembodiments, individual ones of the microelectronic assemblies 100disclosed herein may serve as a system-in-package (SiP) in whichmultiple dies 114 having different functionality are included. In suchembodiments, the microelectronic assembly 100 may be referred to as anSiP.

The microelectronic assembly 100 may include a package substrate 102coupled to a die 114-1 by die-to-package substrate (DTPS) interconnects150-1. In particular, the top surface of the package substrate 102 mayinclude a set of conductive contacts 146, and the bottom surface of thedie 114-1 may include a set of conductive contacts 122; the conductivecontacts 122 at the bottom surface of the die 114-1 may be electricallyand mechanically coupled to the conductive contacts 146 at the topsurface of the package substrate 102 by the DTPS interconnects 150-1. Inthe embodiment of FIG. 1, the top surface of the package substrate 102includes a recess 108 in which the die 114-1 is at least partiallydisposed; the conductive contacts 146 to which the die 114-1 is coupledare located at the bottom of the recess 108. In other embodiments, thedie 114-1 may not be disposed in a recess (e.g., as discussed below withreference to FIGS. 9-11). Any of the conductive contacts disclosedherein (e.g., the conductive contacts 122, 124, 146, 140, and/or 135)may include bond pads, posts, or any other suitable conductive contact,for example, and the DTPS interconnects 150 may include any suitablefirst-level interconnect. The package substrate 102 may include other ordifferent features (not shown), such as cores, solder resists, etc.

The package substrate 102 may include an insulating material (e.g., adielectric material formed in multiple layers, as known in the art) andone or more conductive pathways through the dielectric material (e.g.,including conductive traces and/or conductive vias, as shown). In someembodiments, the insulating material of the package substrate 102 may bea dielectric material, such as an organic dielectric material, afire-retardant grade 4 material (FR-4), bismaleimide triazine (BT)resin, polyimide materials, glass reinforced epoxy matrix materials, orlow-k and ultra low-k dielectric (e.g., carbon-doped dielectrics,fluorine-doped dielectrics, porous dielectrics, and organic polymericdielectrics). In particular, when the package substrate 102 is formedusing standard printed circuit board (PCB) processes, the packagesubstrate 102 may include FR-4, and the conductive pathways in thepackage substrate 102 may be formed by patterned sheets of copperseparated by build-up layers of the FR-4. The conductive pathways in thepackage substrate 102 may be bordered by liner materials, such asadhesion liners and/or barrier liners, as suitable.

In some embodiments, one or more of the conductive pathways in thepackage substrate 102 may extend between a conductive contact 146 at thetop surface of the package substrate 102 and a conductive contact 140 atthe bottom surface of the package substrate 102. In some embodiments,one or more of the conductive pathways in the package substrate 102 mayextend between a conductive contact 146 at the bottom of the recess 108and a conductive contact 140 at the bottom surface of the packagesubstrate 102. In some embodiments, one or more of the conductivepathways in the package substrate 102 may extend between differentconductive contacts 146 at the top surface of the package substrate 102(e.g., between a conductive contact 146 at the bottom of the recess 108and a different conductive contact 146 at the top surface of the packagesubstrate 102). In some embodiments, one or more of the conductivepathways in the package substrate 102 may extend between differentconductive contacts 140 at the bottom surface of the package substrate102.

The dies 114 disclosed herein may include an insulating material (e.g.,a dielectric material formed in multiple layers, as known in the art)and multiple conductive pathways formed through the insulating material.In some embodiments, the insulating material of a die 114 may include adielectric material, such as silicon dioxide, silicon nitride,oxynitride, polyimide materials, glass reinforced epoxy matrixmaterials, or a low-k or ultra low-k dielectric (e.g., carbon-dopeddielectrics, fluorine-doped dielectrics, porous dielectrics, organicpolymeric dielectrics, photo-imageable dielectrics, and/orbenzocyclobutene-based polymers). In some embodiments, the insulatingmaterial of a die 114 may include a semiconductor material, such assilicon, germanium, or a III-V material (e.g., gallium nitride), and oneor more additional materials. For example, an insulating material mayinclude silicon oxide or silicon nitride. The conductive pathways in adie 114 may include conductive traces and/or conductive vias, and mayconnect any of the conductive contacts in the die 114 in any suitablemanner (e.g., connecting multiple conductive contacts on a same surfaceor on different surfaces of the die 114). Example structures that may beincluded in the dies 114 disclosed herein are discussed below withreference to FIG. 32. The conductive pathways in the dies 114 may bebordered by liner materials, such as adhesion liners and/or barrierliners, as suitable.

In some embodiments, the die 114-1 may include conductive pathways toroute power, ground, and/or signals to/from some of the other dies 114included in the microelectronic assembly 100. For example, the die 114-1may include through-substrate vias (TSVs, including a conductivematerial via, such as a metal via, isolated from the surrounding siliconor other semiconductor material by a barrier oxide) or other conductivepathways through which power, ground, and/or signals may be transmittedbetween the package substrate 102 and one or more dies 114 “on top” ofthe die 114-1 (e.g., in the embodiment of FIG. 1, the die 114-2 and/orthe die 114-3). In some embodiments, the die 114-1 may includeconductive pathways to route power, ground, and/or signals betweendifferent ones of the dies 114 “on top” of the die 114-1 (e.g., in theembodiment of FIG. 1, the die 114-2 and the die 114-3). In someembodiments, the die 114-1 may be the source and/or destination ofsignals communicated between the die 114-1 and other dies 114 includedin the microelectronic assembly 100.

In some embodiments, the die 114-1 may not route power and/or ground tothe die 114-2; instead, the die 114-2 may couple directly to powerand/or ground lines in the package substrate 102. By allowing the die114-2 to couple directly to power and/or ground lines in the packagesubstrate 102, such power and/or ground lines need not be routed throughthe die 114-1, allowing the die 114-1 to be made smaller or to includemore active circuitry or signal pathways.

In some embodiments, the die 114-1 may only include conductive pathways,and may not contain active or passive circuitry. In other embodiments,the die 114-1 may include active or passive circuitry (e.g.,transistors, diodes, resistors, inductors, and capacitors, amongothers). In some embodiments, the die 114-1 may include one or moredevice layers including transistors (e.g., as discussed below withreference to FIG. 32. When the die 114-1 includes active circuitry,power and/or ground signals may be routed through the package substrate102 and to the die 114-1 through the conductive contacts 122 on thebottom surface of the die 114-1.

Although FIG. 1 illustrates a specific number and arrangement ofconductive pathways in the package of 102 and/or one or more of the dies114, these are simply illustrative, and any suitable number andarrangement may be used. The conductive pathways disclosed herein (e.g.,conductive traces and/or conductive vias) may be formed of anyappropriate conductive material, such as copper, silver, nickel, gold,aluminum, or other metals or alloys, for example.

In some embodiments, the package substrate 102 may be a lower densitymedium and the die 114-1 may be a higher density medium. As used herein,the term “lower density” and “higher density” are relative termsindicating that the conductive pathways (e.g., including conductivelines and conductive vias) in a lower density medium are larger and/orhave a greater pitch than the conductive pathways in a higher densitymedium. In some embodiments, a higher density medium may be manufacturedusing a modified semi-additive process or a semi-additive build-upprocess with advanced lithography (with small vertical interconnectfeatures formed by advanced laser or lithography processes), while alower density medium may be a PCB manufactured using a standard PCBprocess (e.g., a standard subtractive process using etch chemistry toremove areas of unwanted copper, and with coarse vertical interconnectfeatures formed by a standard laser process).

The microelectronic assembly 100 of FIG. 1 may also include a die 114-2.The die 114-2 may be electrically and mechanically coupled to thepackage substrate 102 by DTPS interconnects 150-2, and may beelectrically and mechanically coupled to the die 114-1 by die-to-die(DTD) interconnects 130-1. In particular, the top surface of the packagesubstrate 102 may include a set of conductive contacts 146, and thebottom surface of the die 114-2 may include a set of conductive contacts122; the conductive contacts 122 at the bottom surface of the die 114-1may be electrically and mechanically coupled to the conductive contacts146 at the top surface of the package substrate 102 by the DTPSinterconnects 150-2. Further, the top surface of the die 114-1 mayinclude a set of conductive contacts 124, and the bottom surface of thedie 114-2 may include a set of conductive contacts 124; the conductivecontacts 124 at the bottom surface of the die 114-2 may be electricallyand mechanically coupled to some of the conductive contacts 124 at thetop surface of the die 114-1 by the DTD interconnects 130-1. FIG. 2 is abottom view of the die 114-2 of the microelectronic assembly 100 of FIG.1, showing the “coarser” conductive contacts 122 and the “finer”conductive contacts 124. The die 114-2 of the microelectronic assembly100 may thus be a single-sided die (in the sense that the die 114-2 onlyhas conductive contacts 122/124 on a single surface), and may be amixed-pitch die (in the sense that the die 114-2 has sets of conductivecontacts 122/124 with different pitch). Although FIG. 2 illustrates theconductive contacts 122 and the conductive contacts 124 as each beingarranged in a rectangular array, this need not be the case, and theconductive contacts 122 and 124 may be arranged in any suitable pattern(e.g., hexagonal, rectangular, different arrangements between theconductive contacts 122 and 124, etc.). A die 114 that has DTPSinterconnects 150 and DTD interconnects 130 at the same surface may bereferred to as a mixed-pitch die 114; more generally, a die 114 that hasinterconnects 130 of different pitches at a same surface may be referredto as a mixed-pitch die 114.

The die 114-2 may extend over the die 114-1 by an overlap distance 191.In some embodiments, the overlap distance 191 may be between 0.5millimeters and 5 millimeters (e.g., between 0.75 millimeters and 2millimeters, or approximately 1 millimeter).

The microelectronic assembly 100 of FIG. 1 may also include a die 114-3.The die 114-3 may be electrically and mechanically coupled to the die114-1 by DTD interconnects 130-2. In particular, the bottom surface ofthe die 114-3 may include a set of conductive contacts 124 that areelectrically and mechanically coupled to some of the conductive contacts124 at the top surface of the die 114-1 by the DTD interconnects 130-2.In the embodiment of FIG. 1, the die 114-3 may be a single-sided,single-pitch die; in other embodiments, the die 114-3 may be adouble-sided (or “multi-level,” or “omni-directional”) die, andadditional components may be disposed on the top surface of the die114-3.

As discussed above, in the embodiment of FIG. 1, the die 114-1 mayprovide high-density interconnect routing in a localized area of themicroelectronic assembly 100. In some embodiments, the presence of thedie 114-1 may support direct chip attach of fine-pitch semiconductordies (e.g., the dies 114-2 and 114-3) that cannot be attached entirelydirectly to the package substrate 102. In particular, as discussedabove, the die 114-1 may support trace widths and spacings that are notachievable in the package substrate 102. The proliferation of wearableand mobile electronics, as well as Internet of Things (IoT)applications, are driving reductions in the size of electronic systems,but limitations of the PCB manufacturing process and the mechanicalconsequences of thermal expansion during use have meant that chipshaving fine interconnect pitch cannot be directly mounted to a PCB.Various embodiments of the microelectronic assemblies 100 disclosedherein may be capable of supporting chips with high-densityinterconnects and chips with low-density interconnects withoutsacrificing performance or manufacturability.

The microelectronic assembly 100 of FIG. 1 may also include a die 114-4.The die 114-4 may be electrically and mechanically coupled to thepackage substrate 102 by DTPS interconnects 150-3. In particular, thebottom surface of the die 114-4 may include a set of conductive contacts122 that are electrically and mechanically coupled to some of theconductive contacts 146 at the top surface of the package substrate 102by the DTPS interconnects 150-3. In the embodiment of FIG. 1, the die114-4 may be a single-sided, single-pitch die; in other embodiments, thedie 114-4 may be a double-sided die, and additional components may bedisposed on the top surface of the die 114-4. Additional passivecomponents, such as surface-mount resistors, capacitors, and/orinductors, may be disposed on the top surface or the bottom surface ofthe package substrate 102, or embedded in the package substrate 102.

The microelectronic assembly 100 of FIG. 1 may also include a circuitboard 133. The package substrate 102 may be coupled to the circuit board133 by second-level interconnects 137 at the bottom surface of thepackage substrate 102. In particular, the package substrate 102 mayinclude conductive contacts 140 at its bottom surface, and the circuitboard 133 may include conductive contacts 135 at its top surface; thesecond-level interconnects 137 may electrically and mechanically couplethe conductive contacts 135 and the conductive contacts 140. Thesecond-level interconnects 137 illustrated in FIG. 1 are solder balls(e.g., for a ball grid array arrangement), but any suitable second-levelinterconnects 137 may be used (e.g., pins in a pin grid arrayarrangement or lands in a land grid array arrangement). The circuitboard 133 may be a motherboard, for example, and may have othercomponents attached to it (not shown). The circuit board 133 may includeconductive pathways and other conductive contacts (not shown) forrouting power, ground, and signals through the circuit board 133, asknown in the art. In some embodiments, the second-level interconnects137 may not couple the package substrate 102 to a circuit board 133, butmay instead couple the package substrate 102 to another IC package, aninterposer, or any other suitable component.

The microelectronic assembly 100 of FIG. 1 may also include a moldmaterial 127. The mold material 127 may extend around one or more of thedies 114 on the package substrate 102. In some embodiments, the moldmaterial 127 may extend above one or more of the dies 114 on the packagesubstrate 102. In some embodiments, the mold material 127 may extendbetween one or more of the dies 114 and the package substrate 102 aroundthe associated DTPS interconnects 150; in such embodiments, the moldmaterial 127 may serve as an underfill material. In some embodiments,the mold material 127 may extend between different ones of the dies 114around the associated DTD interconnects 130; in such embodiments, themold material 127 may serve as an underfill material. The mold material127 may include multiple different mold materials (e.g., an underfillmaterial, and a different overmold material). The mold material 127 maybe an insulating material, such as an appropriate epoxy material. Insome embodiments, the mold material 127 may include an underfillmaterial that is an epoxy flux that assists with soldering the dies114-1/114-2 to the package substrate 102 when forming the DTPSinterconnects 150-1 and 150-2, and then polymerizes and encapsulates theDTPS interconnects 150-1 and 150-2. The mold material 127 may beselected to have a coefficient of thermal expansion (CTE) that maymitigate or minimize the stress between the dies 114 and the packagesubstrate 102 arising from uneven thermal expansion in themicroelectronic assembly 100. In some embodiments, the CTE of the moldmaterial 127 may have a value that is intermediate to the CTE of thepackage substrate 102 (e.g., the CTE of the dielectric material of thepackage substrate 102) and a CTE of the dies 114.

The microelectronic assembly 100 of FIG. 1 may also include a thermalinterface material (TIM) 129. The TIM 129 may include a thermallyconductive material (e.g., metal particles) in a polymer or otherbinder. The TIM 129 may be a thermal interface material paste or athermally conductive epoxy (which may be a fluid when applied and mayharden upon curing, as known in the art). The TIM 129 may provide a pathfor heat generated by the dies 114 to readily flow to the heat spreader131, where it may be spread and/or dissipated. Some embodiments of themicroelectronic assembly 100 of FIG. 1 may include a sputtered back sidemetallization (not shown) across the mold material 127 and the dies 114;the TIM 129 (e.g., a solder TIM) may be disposed on this back sidemetallization.

The microelectronic assembly 100 of FIG. 1 may also include a heatspreader 131. The heat spreader 131 may be used to move heat away fromthe dies 114 (e.g., so that the heat may be more readily dissipated by aheat sink or other thermal management device). The heat spreader 131 mayinclude any suitable thermally conductive material (e.g., metal,appropriate ceramics, etc.), and may include any suitable features(e.g., fins). In some embodiments, the heat spreader 131 may be anintegrated heat spreader.

The DTPS interconnects 150 disclosed herein may take any suitable form.In some embodiments, a set of DTPS interconnects 150 may include solder(e.g., solder bumps or balls that are subject to a thermal reflow toform the DTPS interconnects 150). DTPS interconnects 150 that includesolder may include any appropriate solder material, such as lead/tin,tin/bismuth, eutectic tin/silver, ternary tin/silver/copper, eutectictin/copper, tin/nickel/copper, tin/bismuth/copper, tin/indium/copper,tin/zinc/indium/bismuth, or other alloys. In some embodiments, a set ofDTPS interconnects 150 may include an anisotropic conductive material,such as an anisotropic conductive film or an anisotropic conductivepaste. An anisotropic conductive material may include conductivematerials dispersed in a non-conductive material. In some embodiments,an anisotropic conductive material may include microscopic conductiveparticles embedded in a binder or a thermoset adhesive film (e.g., athermoset biphenyl-type epoxy resin, or an acrylic-based material). Insome embodiments, the conductive particles may include a polymer and/orone or more metals (e.g., nickel or gold). For example, the conductiveparticles may include nickel-coated gold or silver-coated copper that isin turn coated with a polymer. In another example, the conductiveparticles may include nickel. When an anisotropic conductive material isuncompressed, there may be no conductive pathway from one side of thematerial to the other. However, when the anisotropic conductive materialis adequately compressed (e.g., by conductive contacts on either side ofthe anisotropic conductive material), the conductive materials near theregion of compression may contact each other so as to form a conductivepathway from one side of the film to the other in the region ofcompression.

The DTD interconnects 130 disclosed herein may take any suitable form.The DTD interconnects 130 may have a finer pitch than the DTPSinterconnects 150 in a microelectronic assembly. In some embodiments,the dies 114 on either side of a set of DTD interconnects 130 may beunpackaged dies, and/or the DTD interconnects 130 may include smallconductive bumps or pillars (e.g., copper bumps or pillars) attached tothe conductive contacts 124 by solder. The DTD interconnects 130 mayhave too fine a pitch to couple to the package substrate 102 directly(e.g., to fine to serve as DTPS interconnects 150). In some embodiments,a set of DTD interconnects 130 may include solder. DTD interconnects 130that include solder may include any appropriate solder material, such asany of the materials discussed above. In some embodiments, a set of DTDinterconnects 130 may include an anisotropic conductive material, suchas any of the materials discussed above. In some embodiments, the DTDinterconnects 130 may be used as data transfer lanes, while the DTPSinterconnects 150 may be used for power and ground lines, among others.

In some embodiments, some or all of the DTD interconnects 130 in amicroelectronic assembly 100 may be metal-to-metal interconnects (e.g.,copper-to-copper interconnects, or plated interconnects). In suchembodiments, the conductive contacts 124 on either side of the DTDinterconnect 130 may be bonded together (e.g., under elevated pressureand/or temperature) without the use of intervening solder or ananisotropic conductive material. In some embodiments, one side of a DTDinterconnect 130 may include a metal pillar (e.g., a copper pillar), andthe other side of the DTD interconnect may include a metal contact(e.g., a copper contact) recessed in a dielectric. In some embodiments,a thin cap of solder may be used in a metal-to-metal interconnect toaccommodate planarity, and this solder may become an intermetalliccompound during processing. In some metal-to-metal interconnects thatutilize hybrid bonding, a dielectric material (e.g., silicon oxide,silicon nitride, silicon carbide, or an organic layer) may be presentbetween the metals bonded together (e.g., between copper pads or poststhat provide the associated conductive contacts 124). In someembodiments, a metal-to-metal interconnect (e.g., a copper-to-copperinterconnect) may include a noble metal (e.g., gold) or a metal whoseoxides are conductive (e.g., silver). In some embodiments, ametal-to-metal interconnect may include metal nanostructures (e.g.,nanorods) that may have a reduced melting point. Metal-to-metalinterconnects may be capable of reliably conducting a higher currentthan other types of interconnects; for example, some solderinterconnects may form brittle intermetallic compounds when currentflows, and the maximum current provided through such interconnects maybe constrained to mitigate mechanical failure.

In some embodiments, some or all of the DTD interconnects 130 in amicroelectronic assembly 100 may be solder interconnects that include asolder with a higher melting point than a solder included in some or allof the DTPS interconnects 150. For example, when the DTD interconnects130 in a microelectronic assembly 100 are formed before the DTPSinterconnects 150 are formed (e.g., as discussed below with reference toFIGS. 17A-17F), solder-based DTD interconnects 130 may use ahigher-temperature solder (e.g., with a melting point above 200 degreesCelsius), while the DTPS interconnects 150 may use a lower-temperaturesolder (e.g., with a melting point below 200 degrees Celsius). In someembodiments, a higher-temperature solder may include tin; tin and gold;or tin, silver, and copper (e.g., 96.5% tin, 3% silver, and 0.5%copper). In some embodiments, a lower-temperature solder may include tinand bismuth (e.g., eutectic tin bismuth) or tin, silver, and bismuth. Insome embodiments, a lower-temperature solder may include indium, indiumand tin, or gallium.

In the microelectronic assemblies 100 disclosed herein, some or all ofthe DTPS interconnects 150 may have a larger pitch than some or all ofthe DTD interconnects 130. DTD interconnects 130 may have a smallerpitch than DTPS interconnects 150 due to the greater similarity ofmaterials in the different dies 114 on either side of a set of DTDinterconnects 130 than between the die 114 and the package substrate 102on either side of a set of DTPS interconnects 150. In particular, thedifferences in the material composition of a die 114 and a packagesubstrate 102 may result in differential expansion and contraction ofthe die 114 and the package substrate 102 due to heat generated duringoperation (as well as the heat applied during various manufacturingoperations). To mitigate damage caused by this differential expansionand contraction (e.g., cracking, solder bridging, etc.), the DTPSinterconnects 150 may be formed larger and farther apart than DTDinterconnects 130, which may experience less thermal stress due to thegreater material similarity of the pair of dies 114 on either side ofthe DTD interconnects. In some embodiments, the DTPS interconnects 150disclosed herein may have a pitch between 80 microns and 300 microns,while the DTD interconnects 130 disclosed herein may have a pitchbetween 7 microns and 100 microns.

The elements of the microelectronic assembly 100 may have any suitabledimensions. Only a subset of the accompanying figures are labeled withreference numerals representing dimensions, but this is simply forclarity of illustration, and any of the microelectronic assemblies 100disclosed herein may have components having the dimensions discussedherein. For example, in some embodiments, the thickness 164 of thepackage substrate 102 may be between 0.1 millimeters and 1.4 millimeters(e.g., between 0.1 millimeters and 0.35 millimeters, between 0.25millimeters and 0.8 millimeters, or approximately 1 millimeter). In someembodiments, the recess 108 may have a depth 175 between 10 microns and200 microns (e.g., between 10 microns and 30 microns, between 30 micronsand 100 microns, between 60 microns and 80 microns, or approximately 75microns). In some embodiments, the depth 175 may be equal to a certainnumber of layers of the dielectric material in the package substrate102. For example, the depth 175 may be approximately equal to betweenone and five layers of the dielectric material in the package substrate102 (e.g., two or three layers of the dielectric material). In someembodiments, the depth 175 may be equal to or less than the thickness ofa solder resist material (not shown) on the top surface of the packagesubstrate 102.

In some embodiments, the distance 179 between the bottom surface of thedie 114-1 and the proximate top surface of the package substrate 102 (atthe bottom of the recess 108) may be less than the distance 177 betweenthe bottom surface of the die 114-2 and the proximate top surface of thepackage substrate 102. In some embodiments, the distance 179 may beapproximately the same as the distance 177. In some embodiments, thedistance 177 between the bottom surface of the die 114-2 and theproximate top surface of the package substrate 102 may be greater thanthe distance 193 between the bottom surface of the die 114-2 and theproximate top surface of the die 114-1. In other embodiments, thedistance 177 may be less than or equal to the distance 193.

In some embodiments, the top surface of the die 114-1 may extend higherthan the top surface of the package substrate 102, as illustrated inFIG. 1. In other embodiments, the top surface of the die 114-1 may besubstantially coplanar with the top surface of the package substrate102, or may be recessed below the top surface of the package substrate102. FIG. 3 illustrates an example of the former embodiment. Althoughvarious ones of the figures illustrate microelectronic assemblies 100having a single recess 108 in the package substrate 102, the thicknessof 102 may include multiple recesses 108 (e.g., having the same ordifferent dimensions, and each having a die 114 disposed therein), or norecesses 108. Examples of the former embodiments are discussed belowwith reference to FIGS. 7-8, and examples of the latter embodiments arediscussed below with reference to FIGS. 9-11. In some embodiments, arecess 108 may be located at the bottom surface of the package substrate102 (e.g., proximate to the conductive contacts 140), instead of or inaddition to a recess 108 at the top surface of the package substrate102.

In the embodiment of FIG. 1, a single die 114-2 is illustrated as“spanning” the package substrate 102 and the die 114-1. In someembodiments of the microelectronic assemblies 100 disclosed herein,multiple dies 114 may span the package substrate 102 and another die114. For example, FIG. 4 illustrates an embodiment in which two dies114-2 each have conductive contacts 122 and conductive contacts 124disposed at the bottom surfaces; the conductive contacts 122 of the dies114-2 are coupled to conductive contacts 146 at the top surface of thepackage substrate 102 via DTPS interconnects 150-2, and the conductivecontacts 124 of the dies 114-2 are coupled to conductive contacts 124 atthe top surface of the die 114 via DTD interconnects 130. In someembodiments, power and/or ground signals may be provided directly to thedies 114 of the microelectronic assembly 100 of FIG. 4 through thepackage substrate 102, and the die 114-1 may, among other things, routesignals between the dies 114-2.

In some embodiments, the die 114-1 may be arranged as a bridge betweenmultiple other dies 114, and may also have additional dies 114 disposedthereon. For example, FIG. 5 illustrates an embodiment in which two dies114-2 each have conductive contacts 122 and conductive contacts 124disposed at the bottom surfaces; the conductive contacts 122 of the dies114-2 are coupled to conductive contacts 146 at the top surface of thepackage substrate 102 via DTPS interconnects 150-2, and the conductivecontacts 124 of the dies 114-2 are coupled to conductive contacts 124 atthe top surface of the die 114 via DTD interconnects 130 (e.g., asdiscussed above with reference to FIG. 4). Additionally, a die 114-3 (ormultiple dies 114-3, not shown) is coupled to the die 114-1 byconductive contacts 124 on proximate surfaces of these dies 114 andintervening DTD interconnects 130-2 (e.g., as discussed above withreference to FIG. 1).

As noted above, any suitable number of the dies 114 in a microelectronicassembly 100 may be double-sided dies 114. For example, FIG. 6illustrates a microelectronic assembly 100 sharing a number of elementswith FIG. 1, but including a double-sided die 114-6. The die 114-6includes conductive contacts 122 and 124 at its bottom surface; theconductive contacts 122 at the bottom surface of the die 114-6 arecoupled to conductive contacts 146 at the top surface of the packagesubstrate 102 via DTPS interconnects 150-2, and the conductive contacts124 at the bottom surface of the die 114-6 are coupled to conductivecontacts 124 at the top surface of the die 114-1 via DTD interconnects130-1. The die 114-6 also includes conductive contacts 124 at its topsurface; these conductive contacts 124 are coupled to conductivecontacts 124 at the bottom surface of a die 114-7 by DTD interconnects130-3.

As noted above, a package substrate 102 may include one or more recesses108 in which dies 114 are at least partially disposed. For example, FIG.7 illustrates a microelectronic assembly 100 including a packagesubstrate 102 having two recesses: a recess 108-1 and a recess 108-2. Inthe embodiment of FIG. 7, the recess 108-1 is nested in the recess108-2, but in other embodiments, multiple recesses 108 need not benested. In FIG. 7, the die 114-1 is at least partially disposed in therecess 108-1, and the dies 114-6 and 114-3 are at least partiallydisposed in the recess 108-2. In the embodiment of FIG. 7, like theembodiment of FIG. 6, the die 114-6 includes conductive contacts 122 and124 at its bottom surface; the conductive contacts 122 at the bottomsurface of the die 114-6 are coupled to conductive contacts 146 at thetop surface of the package substrate 102 via DTPS interconnects 150-2,and the conductive contacts 124 at the bottom surface of the die 114-6are coupled to conductive contacts 124 at the top surface of the die114-1 via DTD interconnects 130-1. The die 114-6 also includesconductive contacts 124 at its top surface; these conductive contacts124 are coupled to conductive contacts 124 at the bottom surface of adie 114-7 by DTD interconnects 130-3. Further, the microelectronicassembly 100 of FIG. 7 includes a die 114-8 that spans the packagesubstrate 102 and the die 114-6. In particular, the die 114-8 includesconductive contacts 122 and 124 at its bottom surface; the conductivecontacts 122 at the bottom surface of the die 114-8 are coupled toconductive contacts 146 at the top surface of the package substrate 102via DTPS interconnects 150-3, and the conductive contacts 124 at thebottom surface of the die 114-8 are coupled to conductive contacts 124at the top surface of the die 114-6 via DTD interconnects 130-4.

In various ones of the microelectronic assemblies 100 disclosed herein,a single die 114 may bridge to other dies 114 from “below” (e.g., asdiscussed above with reference to FIGS. 4 and 5) or from “above.” Forexample, FIG. 8 illustrates a microelectronic assembly 100 similar tothe microelectronic assembly 100 of FIG. 7, but including twodouble-sided dies 114-9 and 114-10, as well as an additional die 114-11.The die 114-9 includes conductive contacts 122 and 124 at its bottomsurface; the conductive contacts 122 at the bottom surface of the die114-9 are coupled to conductive contacts 146 at the top surface of thepackage substrate 102 via DTPS interconnects 150-3, and the conductivecontacts 124 at the bottom surface of the die 114-9 are coupled toconductive contacts 124 at the top surface of the die 114-6 via DTDinterconnects 130-4. The die 114-6 includes conductive contacts 124 atits top surface; these conductive contacts 124 are coupled to conductivecontacts 124 at the bottom surface of a die 114-10 by DTD interconnects130-3. Further, the die 114-11 includes conductive contacts 124 at itsbottom surface; some of these conductive contacts 124 are coupled toconductive contacts 124 at the top surface of the die 114-9 by DTDinterconnects 130-6, and some of these conductive contacts 124 arecoupled to conductive contacts 124 at the top surface of the die 114-10by DTD interconnects 130-5. The die 114-11 may thus bridge the dies114-9 and 114-10.

As noted above, in some embodiments, the package substrate 102 may notinclude any recesses 108. For example, FIG. 9 illustrates an embodimenthaving dies 114 and a package substrate 102 mutually interconnected inthe manner discussed above with reference to FIG. 1, but in which thedie 114-1 is not disposed in a recess in the package substrate 102.Instead, the dies 114 are disposed above a planar portion of the topsurface of the package substrate 102. Any suitable ones of theembodiments disclosed herein that include recesses 108 may havecounterpart embodiments that do not include a recess 108. For example,FIG. 10 illustrates a microelectronic assembly 100 having dies 114 and apackage substrate 102 mutually interconnected in the manner discussedabove with reference to FIG. 4, but in which the die 114-1 is notdisposed in a recess in the package substrate 102.

Any of the arrangements of dies 114 illustrated in any of theaccompanying figures may be part of a repeating pattern in amicroelectronic assembly 100. For example, FIG. 11 illustrates a portionof a microelectronic assembly 100 in which an arrangement like the oneof FIG. 10 is repeated, with multiple dies 114-1 and multiple dies114-2. The dies 114-1 may bridge the adjacent dies 114-2. Moregenerally, the microelectronic assemblies 100 disclosed herein mayinclude any suitable arrangement of dies 114. FIGS. 12-16 are top viewsof example arrangements of multiple dies 114 in various microelectronicassemblies 100, in accordance with various embodiments. The packagesubstrate 102 is omitted from FIGS. 12-16; some or all of the dies 114in these arrangements may be at least partially disposed in a recess 108in a package substrate 102, or may not be disposed in a recess of apackage substrate 102. In the arrangements of FIGS. 12-16, the differentdies 114 may include any suitable circuitry. For example, in someembodiments, the die 114A may be an active or passive die, and the dies114B may include input/output circuitry, high bandwidth memory, and/orenhanced dynamic random access memory (EDRAM). The arrays of FIGS. 12-16are largely rectangular, but dies 114 may be positioned in any suitablearrangement (e.g., a non-rectangular array, such as a triangular array,a hexagonal array, etc.). Further, although dies 114 having rectangularfootprints are illustrated herein, the dies 114 may have any desiredfootprints (e.g., triangular, hexagonal, etc.), and such dies 114 may bearranged in any desired array (e.g., triangular, hexagonal, etc.).

FIG. 12 illustrates an arrangement in which a die 114A is disposed belowmultiple different dies 114B. The die 114A may be connected to a packagesubstrate 102 (not shown) in any of the manners disclosed herein withreference to the die 114-1, while the dies 114B may span the packagesubstrate 102 and the die 114A (e.g., in any of the manners disclosedherein with reference to the die 114-2). FIG. 12 also illustrates a die114C disposed on the die 114A (e.g., in the manner disclosed herein withreference to the die 114-3). In FIG. 12, the dies 114B “overlap” theedges and/or the corners of the die 114A, while the die 114C is whollyabove the die 114A. Placing dies 114B at least partially over thecorners of the die 114A may reduce routing congestion in the die 114Aand may improve utilization of the die 114A (e.g., in case the number ofinput/outputs needed between the die 114A and the dies 114B is not largeenough to require the full edge of the die 114A). In some embodiments,the die 114A may be disposed in a recess 108 in a package substrate 102.In some embodiments, the die 114A may be disposed in a recess 108 in apackage substrate 102, and the dies 114B may be disposed in one or morerecesses 108 in the package substrate 102. In some embodiments, none ofthe dies 114A or 114B may be disposed in recesses 108.

FIG. 13 illustrates an arrangement in which a die 114A is disposed belowmultiple different dies 114B. The die 114A may be connected to a packagesubstrate 102 (not shown) in any of the manners disclosed herein withreference to the die 114-1, while the dies 114B may span the packagesubstrate 102 and the die 114A (e.g., in any of the manners disclosedherein with reference to the die 114-2). FIG. 13 also illustrates dies114C disposed on the die 114A (e.g., in the manner disclosed herein withreference to the die 114-3). In FIG. 13, the dies 114B “overlap” theedges of the die 114A, while the dies 114C are wholly above the die114A. In some embodiments, the die 114A may be disposed in a recess 108in a package substrate 102. In some embodiments, the die 114A may bedisposed in a recess 108 in a package substrate 102, and the dies 114Bmay be disposed in one or more recesses 108 in the package substrate102. In some embodiments, none of the dies 114A or 114B may be disposedin recesses 108. In the embodiment of FIG. 13, the dies 114B and 114Cmay be arranged in a portion of a rectangular array. In someembodiments, two dies 114A may take the place of the single die 114Aillustrated in FIG. 13, and one or more dies 114C may “bridge” the twodies 114A (e.g., in the manner discussed below with reference to FIG.15).

FIG. 14 illustrates an arrangement in which a die 114A is disposed belowmultiple different dies 114B. The die 114A may be connected to a packagesubstrate 102 (not shown) in any of the manners disclosed herein withreference to the die 114-1, while the dies 114B may span the packagesubstrate 102 and the die 114A (e.g., in any of the manners disclosedherein with reference to the die 114-2). In FIG. 14, the dies 114B“overlap” the edges and/or the corners of the die 114A. In someembodiments, the die 114A may be disposed in a recess 108 in a packagesubstrate 102. In some embodiments, the die 114A may be disposed in arecess 108 in a package substrate 102, and the dies 114B may be disposedin one or more recesses 108 in the package substrate 102. In someembodiments, none of the dies 114A or 114B may be disposed in recesses108. In the embodiment of FIG. 14, the dies 114B may be arranged in aportion of a rectangular array.

FIG. 15 illustrates an arrangement in which multiple dies 114A aredisposed below multiple different dies 114B such that each die 114Abridges two or more horizontally or vertically adjacent dies 114B. Thedies 114A may be connected to a package substrate 102 (not shown) in anyof the manners disclosed herein with reference to the die 114-1, whilethe dies 114B may span the package substrate 102 and the die 114A (e.g.,in any of the manners disclosed herein with reference to the die 114-2).In FIG. 12, the dies 114B “overlap” the edges of the adjacent dies 114A.In some embodiments, the dies 114A may be disposed in one or morerecesses 108 in a package substrate 102. In some embodiments, the dies114A may be disposed in one or more recesses 108 in a package substrate102, and the dies 114B may be disposed in one or more recesses 108 inthe package substrate 102. In some embodiments, none of the dies 114A or114B may be disposed in recesses 108. In FIG. 15, the dies 114A and thedies 114B may be arranged in rectangular arrays.

FIG. 16 illustrates an arrangement in which multiple dies 114A aredisposed below multiple different dies 114B such that each die 114Abridges the four diagonally adjacent dies 114B. The dies 114A may beconnected to a package substrate 102 (not shown) in any of the mannersdisclosed herein with reference to the die 114-1, while the dies 114Bmay span the package substrate 102 and the die 114A (e.g., in any of themanners disclosed herein with reference to the die 114-2). In FIG. 12,the dies 114B “overlap” the corners of the adjacent dies 114A. In someembodiments, the dies 114A may be disposed in one or more recesses 108in a package substrate 102. In some embodiments, the dies 114A may bedisposed in one or more recesses 108 in a package substrate 102, and thedies 114B may be disposed in one or more recesses 108 in the packagesubstrate 102. In some embodiments, none of the dies 114A or 114B may bedisposed in recesses 108. In FIG. 16, the dies 114A and the dies 114Bmay be arranged in rectangular arrays.

Any suitable techniques may be used to manufacture the microelectronicassemblies disclosed herein. For example, FIGS. 17A-17F are side,cross-sectional views of various stages in an example process formanufacturing the microelectronic assembly 100 of FIG. 5, in accordancewith various embodiments. Although the operations discussed below withreference to FIGS. 17A-17F (and others of the accompanying drawingsrepresenting manufacturing processes) are illustrated in a particularorder, these operations may be performed in any suitable order.Additionally, although particular assemblies are illustrated in FIGS.17A-17F (and others of the accompanying drawings representingmanufacturing processes), the operations discussed below with referenceto FIGS. 17A-17F may be used to form any suitable assemblies. In someembodiments, microelectronic assemblies 100 manufactured in accordancewith the process of FIGS. 17A-17F (e.g., any of the microelectronicassemblies 100 of FIGS. 1-11) may have DTPS interconnects 150-1 that aresolder interconnects, and DTD interconnects 130-1 and 130-2 that arenon-solder interconnects (e.g., metal-to-metal interconnects oranisotropic conductive material interconnects). In the embodiment ofFIGS. 17A-17F, the dies 114 may first be assembled into a “compositedie,” and then the composite die may be coupled to the package substrate102. This approach may allow for tighter tolerances in the formation ofthe DTD interconnects 130, and may be particularly desirable forrelatively small dies 114.

FIG. 17A illustrates an assembly 300 including a carrier 202 on whichthe dies 114-2 and 114-3 are disposed. The dies 114-2 and 114-3 are“upside down” on the carrier 202, in the sense that the conductivecontacts 122 and 124 of the dies 114 are facing away from the carrier202, and the conductive contacts 124 of the die 114-3 are facing awayfrom the carrier 202. The dies 114-2 and 114-3 may be secured to thecarrier using any suitable technique, such as a removable adhesive. Thecarrier 202 may include any suitable material for providing mechanicalstability during subsequent manufacturing operations.

FIG. 17B illustrates an assembly 302 subsequent to coupling the die114-1 to the dies 114-2 and 114-3. In particular, the die 114-1 may bearranged “upside down” in the assembly 302 such that the conductivecontacts 124 of the die 114-1 may be coupled to the conductive contacts124 of the dies 114-2 (via DTD interconnects 130-1) and to theconductive contacts 124 of the die 114-3 (via DTD interconnects 130-2).Any suitable technique may be used to form the DTD interconnects 130 ofthe assembly 302, such as metal-to-metal attachment techniques, soldertechniques, or anisotropic conductive material techniques.

FIG. 17C illustrates an assembly 304 including a package substrate 203.The package substrate 203 may be structurally similar to the packagesubstrate 102 of FIG. 5, but may not include the recess 108 of thepackage substrate 102. In some embodiments, the package substrate 203may be manufactured using standard PCB manufacturing processes, and thusthe package substrate 203 may take the form of a PCB, as discussedabove. In some embodiments, the package substrate 203 may be a set ofredistribution layers formed on a panel carrier (not shown) bylaminating or spinning on a dielectric material, and creating conductivevias and lines by laser drilling and plating. Any method known in theart for fabrication of the package substrate 203 may be used, and forthe sake of brevity, such methods will not be discussed in furtherdetail herein.

FIG. 17D illustrates an assembly 306 subsequent to forming a recess 108in the package substrate 203 (FIG. 17C) to form the package substrate102. The recess 108 may have a bottom surface at which conductivecontacts 146 are exposed. Any suitable technique may be used to form therecess 108. For example, in some embodiments, the recess 108 may belaser-drilled down to a planar metal stop in the package substrate 203(not shown); once the metal stop is reached, the metal stop may beremoved to expose the conductive contacts 146 at the bottom of therecess 108. In some embodiments, the recess 108 may be formed by amechanical drill.

FIG. 17E illustrates an assembly 308 subsequent to “flipping” theassembly 302 (FIG. 17B) and bringing the dies 114-1 and 114-2 intoalignment with the package substrate 102 (FIG. 17D) so that theconductive contacts 122 on the dies 114-1 and 114-2 are aligned withtheir respective conductive contacts 146 on the top surface of thepackage substrate 102.

FIG. 17F illustrates an assembly 310 subsequent to forming DTPSinterconnects 150 between the dies 114-1/114-2 and the package substrate102 of the assembly 308 (FIG. 17E), then removing the carrier. The DTPSinterconnects 150 may take any of the forms disclosed herein (e.g.,solder interconnects, or anisotropic conductive material interconnects),and any suitable techniques may be used to form the DTPS interconnects150 (e.g., a mass reflow process or a thermal compression bondingprocess). The assembly 310 may take the form of the microelectronicassembly 100 of FIG. 5. Further operations may be performed as suitable(e.g., providing a mold material 127, providing a TIM 129, providing aheat spreader 131, attaching additional dies 114 to the packagesubstrate 102, etc.).

FIGS. 18A-18B are side, cross-sectional views of various stages inanother example process for manufacturing the microelectronic assembly100 of FIG. 5, in accordance with various embodiments. In someembodiments, microelectronic assemblies 100 manufactured in accordancewith the process of FIGS. 18A-18B (e.g., any of the microelectronicassemblies 100 of FIGS. 1-11) may have DTPS interconnects 150-1 that aresolder interconnects, and DTD interconnects 130-1 and 130-2 that arealso solder interconnects. In the embodiment of FIGS. 18A-18B, the die114-1 may be coupled to the package substrate 102, and then theremaining dies 114 may be attached. This approach may accommodate thetolerance and warpage of the package substrate 102, and may beparticularly desirable for relatively larger dies 114. The process ofFIGS. 17A-17F may advantageously be more compatible with non-solder DTDinterconnects 130, while the process of FIGS. 18A-18B may advantageouslyinvolve simpler handling of the dies 114.

FIG. 18A illustrates an assembly 312 subsequent to coupling the die114-1 to the package substrate 102. In particular, the die 114-1 may bepositioned in the recess 108, and conductive contacts 122 at the bottomsurface of the die 114-1 may be coupled to conductive contacts 146 atthe top surface of the package substrate 102 by DTPS interconnects150-1. The DTPS interconnects 150-1 may take the form of any of theembodiments disclosed herein, such as solder interconnects oranisotropic conductive material interconnects. The package substrate 102may be formed in accordance with any of the techniques discussed abovewith reference to FIGS. 17C-17D.

FIG. 18B illustrates an assembly 314 subsequent to coupling the dies114-2 and 114-3 to the assembly 312 (FIG. 18A). In particular, theconductive contacts 124 of the die 114-1 may be coupled to theconductive contacts 124 of the dies 114-2 (via DTD interconnects 130-1)and to the conductive contacts 124 of the die 114-3 (via DTDinterconnects 130-2). Further, the conductive contacts 122 of the dies114-2 may be coupled to conductive contacts 146 at the top surface ofthe package substrate 102 via DTPS interconnects 150-2. Any suitabletechnique may be used to form the DTD interconnects 130-1 and 130-2, andthe DTPS interconnects 150-2, of the assembly 314, such as soldertechniques or anisotropic conductive material techniques. For example,the DTPS interconnects 150-2 and the DTD interconnects 130-1/130-2 maybe solder interconnects. The assembly 314 may take the form of themicroelectronic assembly 100 of FIG. 5. Further operations may beperformed as suitable (e.g., providing a mold material 127, providing aTIM 129, providing a heat spreader 131, attaching additional dies 114 tothe package substrate 102, etc.).

FIGS. 19A-19H are side, cross-sectional views of various stages inanother example process for manufacturing the microelectronic assembly100 of FIG. 5, in accordance with various embodiments. In someembodiments, microelectronic assemblies 100 manufactured in accordancewith the process of FIGS. 19A-19H (e.g., any of the microelectronicassemblies 100 of FIGS. 1-11) may have DTPS interconnects 150-1 that arenon-solder interconnects (e.g., anisotropic conductive materialinterconnects), and DTD interconnects 130-1 and 130-2 that are solderinterconnects.

FIG. 19A illustrates an assembly 315 including a package substrateportion 113 on a carrier 202. The package substrate portion 113 may bethe “top” portion of the package substrate 102, as discussed furtherbelow, and may include conductive contacts 146 at the surface of thepackage substrate portion 113 facing away from the carrier 202. Thecarrier 202 may take any of the forms disclosed herein. The packagesubstrate portion 113 may be formed on the carrier 202 using anysuitable technique, such as a redistribution layer technique.

FIG. 19B illustrates an assembly 316 subsequent to forming a cavity 111in the package substrate portion 113 of the assembly 315 (FIG. 19A). Thecavity 111 may be formed using any of the techniques discussed abovewith reference to the recess 108 of FIG. 17D, for example. As discussedin further detail below, the cavity 111 may correspond to the recess108.

FIG. 19C illustrates an assembly 318 subsequent to positioning the die114-1 in the cavity 111 of the assembly 316 (FIG. 19B). The die 114-1may be positioned in the cavity 111 so that the conductive contacts 122face the carrier 202, and the conductive contacts 124 face away from thecarrier 202. In some embodiments, a pick-and-place machine may be usedto position the die 114-1 in the cavity 111 on the carrier 202.

FIG. 19D illustrates an assembly 320 subsequent to coupling the dies114-2 and 114-3 to the assembly 318 (FIG. 19C), and providing a moldmaterial 127 around the dies 114. In particular, the conductive contacts124 of the die 114-1 may be coupled to the conductive contacts 124 ofthe dies 114-2 (via DTD interconnects 130-1) and to the conductivecontacts 124 of the die 114-3 (via DTD interconnects 130-2). Further,the conductive contacts 122 of the dies 114-2 may be coupled toconductive contacts 146 at the top surface of the package substrate 102via DTPS interconnects 150-2. Any suitable technique may be used to formthe DTD interconnects 130-1 and 130-2, and the DTPS interconnects 150-2,of the assembly 314, such as solder techniques or anisotropic conductivematerial techniques. For example, the DTPS interconnects 150-2 and theDTD interconnects 130-1/130-2 may be solder interconnects. The moldmaterial 127 may take any of the forms disclosed herein, and may providemechanical support for further manufacturing operations.

FIG. 19E illustrates an assembly 321 subsequent to attaching anothercarrier 204 to the top surface of the assembly 320 (FIG. 19D). Thecarrier 204 may take the form of any of the embodiments of the carrier202 disclosed herein.

FIG. 19F illustrates an assembly 322 subsequent to removing the carrier202 from the assembly 321 (FIG. 19E) and flipping the result so that thepackage substrate portion 113 and the conductive contacts 122 of the die114-1 are exposed.

FIG. 19G illustrates an assembly 324 subsequent to forming an additionalpackage substrate portion 115 on the package substrate portion 113 ofthe assembly 322 (FIG. 19F) to form the package substrate 102. Anysuitable technique may be used to form the package substrate portion113, including any of the techniques discussed above with reference toFIG. 19A, a bumpless build-up layer technique, a carrier-basedpanel-level coreless package substrate manufacturing technique, or anembedded panel-level bonding technique. In some embodiments, forming thepackage substrate portion 115 may include plating the conductivecontacts 122 of the die 114-1 with a metal or other conductive materialas part of forming the proximate conductive contacts 146 of the packagesubstrate 102; consequently, the DTPS interconnects 150-1 between thedie 114-1 and the package substrate 102 may be plated interconnects.

FIG. 19H illustrates an assembly 325 subsequent to removing the carrier204 from the assembly 324 (FIG. 19G) and flipping the result. Theassembly 325 may take the form of the microelectronic assembly 100 ofFIG. 5. Further operations may be performed as suitable (e.g., providinga TIM 129, providing a heat spreader 131, attaching additional dies 114to the package substrate 102, etc.).

In the microelectronic assemblies 100 discussed above with reference toFIGS. 1-11, the die 114-1 is coupled directly to at least one die 114-2without any intervening portion of the package substrate 102. In otherembodiments of the microelectronic assemblies 100 disclosed herein, aportion of the package substrate 102 may be disposed between an embeddeddie 114-1 and a die 114-2. FIGS. 20-22 are side, cross-sectional viewsof example microelectronic assemblies 100 including such a feature, inaccordance with various embodiments. In particular, FIGS. 20-22illustrate arrangements of dies 114-1, 114-2, 114-3, and 114-4 that aresimilar to the arrangement illustrated in FIG. 1, but that furtherinclude a package substrate portion 148 between the top surface of thedie 114-1 and the top surface of the package substrate 102. The dies114-2, 114-3, and 114-4 may all be coupled to this package substrateportion 148. For example, the die 114-1 may include conductive contacts122 at its bottom surface that couple to conductive contacts 146 of thepackage substrate 102 via DTPS interconnects 150-1, and the die 114-1may include conductive contacts 122 at its top surface that couple toconductive contacts 146 of the package substrate 102 (in the packagesubstrate portion 148) via DTPS interconnects 150-4.

In some embodiments, the package substrate portion 148 may include oneor more areas 149 with higher conductive pathway density (e.g., theareas in which the footprint of the die 114-2 overlaps with thefootprint of the die 114-1 and the package substrate portion 148includes conductive pathways between the die 114-2 and the die 114-1, orthe areas in which the footprint of the die 114-3 overlaps of thefootprint of the die 114-1 and the package substrate portion 148includes conductive pathways between the die 114-3 and the die 114-1).Thus, the die 114-2 may be a mixed-pitch die including larger-pitchconductive contacts 122A and smaller-pitch conductive contacts 122B; thelarger-pitch conductive contacts 122A may couple (through some of theDTPS interconnects 150-2) to conductive contacts 146 on the top surfaceof the package substrate 102 (that themselves couple to conductivepathways through the bulk of the package substrate 102), and thesmaller-pitch conductive contacts 122B may couple (through some of theDTPS interconnects 150-2) to conductive contacts 146 on the top surfaceof the package substrate 102 (that themselves couple to conductivepathways through the package substrate portion 148 and to the die114-1). Similarly, the pitch of the conductive contacts 122 at thebottom surface of the die 114-3 (which may be coupled via the DTPSinterconnects 150-5 to dense conductive pathways through the packagesubstrate portion 148 to the die 114-1) may be smaller than the pitch ofthe conductive contacts 122 at the bottom surface of the die 114-4(which may be coupled via the DTPS interconnects 150-3 to less denseconductive pathways through the package substrate 102). The packagesubstrate 102 may also include a portion 151 adjacent to the die 114-1,and a portion 153 below the die 114-1.

Microelectronic assemblies 100 including embedded dies 114 may includeany suitable arrangement of dies 114. For example, any of thearrangements illustrated in FIGS. 12-16 may be implemented with the die114A embedded in a package substrate, with the dies 114A and 114Bembedded in a package substrate 102, or with the dies 114A, 114B, and114C embedded in a package substrate 102. Additionally, any of thearrangements illustrated in FIGS. 1-11 may be implemented with the die114-1 (and optionally more of the dies 114) embedded in a packagesubstrate 102, in accordance with any of the embodiments of FIGS. 20-22.

Any suitable techniques may be used to manufacture microelectronicassemblies 100 having an embedded die 114-1 (e.g., having a packagesubstrate portion 148 between the die 114-1 and the die 114-2). Forexample, FIGS. 21A-21B are side, cross-sectional views of various stagesin an example process for manufacturing the microelectronic assembly 100of FIG. 20, in accordance with various embodiments. In some embodiments,microelectronic assemblies 100 manufactured in accordance with theprocess of FIGS. 21A-21B may have DTPS interconnects 150-1 that aresolder interconnects, and DTPS interconnects 150-4 that are non-solderinterconnects (e.g., plated interconnects).

FIG. 21A illustrates an assembly 326 subsequent to forming the packagesubstrate portion 148 on the assembly 312 (FIG. 18A). The packagesubstrate portion 148 may be formed using any suitable techniques, suchas any of the techniques discussed above with reference to the formationof the package substrate portion 115 of FIG. 19G. In some embodiments,forming the package substrate portion 148 may include plating theconductive contacts 122 of the die 114-1 with a metal or otherconductive material as part of forming the proximate conductive contacts146 of the package substrate 102; consequently, the DTPS interconnects150-4 between the die 114-1 and the package substrate portion 148 may beplated interconnects.

FIG. 21B illustrates an assembly 328 subsequent to attaching the dies114-2, 114-3, and 114-4 to the assembly 326 (FIG. 21A). Any suitabletechniques may be used to form the DTPS interconnects 150 between thedies 114-2, 114-3, and 114-4 and the package substrate 102, such assolder techniques or anisotropic conductive material techniques.

As discussed above, so microelectronic assemblies 100 may includepackage substrates 102 having one or more recesses 108 therein (e.g., asdiscussed above with reference to FIG. 1, FIG. 3, and FIGS. 4-8).Additionally, some of the micro electronic assemblies 100 disclosedherein may include a package substrate 102 that has a recess formedtherein as part of its manufacturing process (e.g., as discussed abovewith reference to the manufacture of the microelectronic assembly 100 ofFIG. 20 in accordance with the technique illustrated by FIG. 21). Asfurther noted above, in some embodiments, a recess 108 may have a depth175 equal to or less than a thickness of a solder resist material (notshown) on the top surface of the package substrate 102.

More generally, any of the microelectronic assemblies 100 disclosedherein may include a photodefinable material or solder resist materialat the top surface of the package substrate 102 in which one or morerecesses 108 may be defined (e.g., any of the microelectronic assemblies100 discussed above with reference to FIG. 1, FIG. 3, and FIGS. 4-8).Further, any of the microelectronic assemblies 100 whose manufactureincludes the formation of a recess in a package substrate 102 (e.g., asdiscussed above with reference to FIG. 21A) may include the formation ofa recess in a photodefinable material or solder resist material, asdisclosed herein.

FIGS. 22-25 are side, cross-sectional views of package substrates 102that may be included in a microelectronic assembly 100, in accordancewith various embodiments. In particular, the package substrates 102illustrated in FIGS. 22-25 include one or more photodefinable materials138. As used herein, a “photodefinable material” refers to a materialthat includes photocatalytic components that cross-link or render thematerial soluble when exposed to appropriate illumination. Somephotodefinable materials 138 may have a negative tone (i.e., exposure toillumination causes the material to cure in a manner that resistsetching during development) and other photodefinable materials 138 mayhave a positive tone (i.e., exposure to illumination causes the materialto cure in a manner that enhances etching during development). Somephotodefinable materials 138 may be solder resist materials; suchmaterials may come in contact with solder during a reflow process (e.g.,when forming DTPS interconnects 150). In some embodiments, aphotodefinable material 138 that is a solder resist may include bariumand sulfur (e.g., in the form of barium sulfate). In some embodiments, aphotodefinable material 138 that is a solder resist may include a silicafiller in the amount of 70 percent to 90 percent by weight. Somephotodefinable materials may be photoimageable dielectric materials,such as epoxides that include photocatalytic components. In someembodiments, a photodefinable material 138 that is a photoimageabledielectric may include a silica filler in the amount of 20 percent to 30percent by weight. Some photodefinable materials may be build-upmaterials, such as a build-up film. In some embodiments, aphotodefinable material 138 that is a build-up material may include asilica filler in the amount of 70 percent to 80 percent by weight. Otherphotodefinable materials 138 may be used as appropriate.

The package substrate 102 of FIG. 22 includes a dielectric material 139,a first photodefinable material 138-1 disposed on the dielectricmaterial 139, and a second photodefinable material 138-2 disposed on thefirst photodefinable material 138-1. The recess 108 is defined bysidewalls 142 provided by the second photodefinable material 138-2.Conductive contacts 146-1 at the bottom of the recess 108 are disposedat the top surface of the dielectric material 139, and DTPSinterconnects 150-1 (illustrated as solder in FIG. 22) are in contactwith the conductive contacts 146-1 through openings in the firstphotodefinable material 138-1. Conductive contacts 146-2 outside of therecess 108 are disposed of the top surface of the dielectric material139, and DTPS interconnects 150-2 (illustrated as solder in FIG. 22) arein contact with the conductive contacts 146-2 through openings in thefirst photodefinable material 138-1 and the second photodefinablematerial 138-2. In some embodiments, the dielectric material 139 may bea build-up film (e.g., an epoxide matrix with silica filler) or any ofthe materials discussed above with reference to the insulating materialof a package substrate 102.

The first photodefinable material 138-1 and the second photodefinablematerial 138-2 may have different material compositions. In someembodiments, the first photodefinable material 138-1 and the secondphotodefinable material 138-2 may have different dose sensitivities(i.e., different illumination energies are needed to pattern thematerials). In some embodiments, the first photodefinable material 138-1and the second photodefinable material 138-2 may be sensitive (e.g.,curable or soluble) to electromagnetic energies of differentwavelengths. For example, the first photodefinable material 138-1 (thesecond photodefinable material 138-2) may be sensitive to I-line light(e.g., with a wavelength of 365 nanometers) and the secondphotodefinable material 138-2 (the first photodefinable material 138-1)may be sensitive to H-line light (e.g., with a wavelength of 405nanometers). In some embodiments, the second photodefinable material138-2 may be sensitive to illumination with a lower photon energy thanthe first photodefinable material 138-1.

In some embodiments, the first photodefinable material 138-1 (secondphotodefinable material 138-2) may have a negative tone, while thesecond photodefinable material 138-2 (first photodefinable material138-1) may have a positive tone. In some embodiments, the firstphotodefinable material 138-1 and the second photodefinable material138-2 may have a same tone (e.g., both positive, or both negative). Insome embodiments, the first photodefinable material 138-1 and the secondphotodefinable material 138-2 may be solder resist materials. In someembodiments, the first photodefinable material 138-1 and the secondphotodefinable material 138-2 may be photoimageable dielectrics. In someembodiments, the first photodefinable material 138-1 may be a solderresist material, and the second photodefinable material 138-2 may be aphotoimageable dielectric. In some embodiments, the secondphotodefinable material 138-2 may include a filler (e.g., silica) at afilling fraction that is greater than a filling fraction of the firstphotodefinable material 138-1; this may improve the resolution of theopenings formed in the first photodefinable material 138-1 relative toembodiments in which the filling fraction of the second photodefinablematerial 138-2 is high (and the second photodefinable material 138-2 isthick).

The dimensions of the package substrate 102 may take any suitablevalues. In some embodiments, the thickness 141-2 of the secondphotodefinable material 138-2 may be greater than the thickness 141-1 ofthe first photodefinable material 138-1. In some embodiments, thethickness 141-1 may be between 10 microns and 75 microns (e.g., between10 microns and 50 microns). In some embodiments, the thickness 141-2 ofthe second photodefinable material 138-2 (and thus the depth 175 of therecess 108) may be between 20 microns and 200 microns. As discussedabove, in some embodiments, the pitch of the conductive contacts 146-1at the bottom of the recess 108 may be greater than the pitch of theconductive contacts 146-2 outside of the recess 108. For example, insome embodiments, the pitch of the conductive contacts 146-1 may bebetween 20 microns and 80 microns, and the pitch of the conductivecontacts 146-2 may be between 80 microns and 200 microns. Otherdimensions of the conductive contacts 146-1 may differ from analogousdimensions of the conductive contacts 146-2 (e.g., diameter of theconductive contacts 146, etc.).

In the embodiment of FIG. 22, the sidewalls 142 of the recess 108 areshown as perpendicular to the top surface of the underlying dielectricmaterial 139. In other embodiments, the angle of the sidewalls 142 maydeviate from perpendicularity. For example, FIG. 23 illustrates anembodiment of a package substrate 102 in which the sidewalls 142 areundercut, providing a taper to the recess 108 that is widest closest tothe dielectric material 139 and narrows toward the top of the recess108. Undercut sidewalls 142 may not be achievable by conventional laserdrilling or routing techniques. In another example, FIG. 24 illustratesan embodiment of the package substrate 102 in which the sidewalls 142are overcut, providing a taper to the recess 108 that is narrowestclosest to the dielectric material 139 and widens toward the top of therecess 108.

In the embodiments of FIGS. 22-24, the openings in the photodefinablematerials 138-1 and 138-2 are shown as being entirely filled with solder(providing DTPS interconnects 150). This need not be the case. Forexample, FIG. 25 illustrates an embodiment of a package substrate 102 inwhich the material of the conductive contacts 146 (or other conductivematerial, such as a metal) extends through the openings in thephotodefinable materials 138-1 and 138-2, and a ball or bump of solderis positioned on these “extended” conductive contact 146 to provide theDTPS interconnects 150.

Although two different photodefinable materials 138 are illustrated inthe embodiments of FIGS. 22-25, more than 2 different photodefinablematerials 138 may be “stacked” on top of a dielectric material 139 andmultiple levels of recesses 108 may be formed therein. For example, the“nested” recesses 108 illustrated in FIGS. 7 and 8 may be formed in aphotodefinable material stack that includes four different layers ofphotodefinable materials that can be selectively patterned (e.g., inaccordance with the techniques discussed below with reference to FIG.27).

Recesses 108 that are formed in photodefinable materials 138 may achievetighter corners than recesses formed by other processes (e.g., routingor laser drilling). For example, FIG. 26 is a top view of a recess 108in a photodefinable material 138-2 in a package substrate 102, inaccordance with various embodiments. Although the recess 108 depicted inFIG. 26 has a substantially square foot print, this is simplyillustrative, and a recess 108 may have any desired footprint (e.g.,triangular, rectangular, polygonal, etc.). In some embodiments, the topview of the recess 108 may have corners 143 with a rounding radius thatis less than 10 microns.

FIGS. 27A-27E are side, cross-sectional views of various stages in anexample process for manufacturing the package substrate 102 of FIG. 22,in accordance with various embodiments. As discussed below, the taper ofthe recess 108 may be selected to be perpendicular (e.g., as illustratedin FIG. 22), undercut (e.g., as illustrated in FIG. 23), or overcut(e.g., as illustrated in FIG. 24) by adjustment of manufacturingconditions. The process illustrated in FIG. 27 may be repeated,extended, or adjusted in order to form any suitable ones of the packagesubstrate 102 disclosed herein.

FIG. 27A illustrates an assembly 330 including a dielectric material 139having conductive contacts 146-1 and 146-2 disposed at its top surface(and conductive contacts 140 disposed at its bottom surface, asdiscussed above), a layer of the first photodefinable material 138-1 onthe dielectric material 139 and conductive contacts 146, and a layer ofthe second photodefinable material 138-2 on the first photodefinablematerial 138-1. In some embodiments, the first photodefinable material138-1 and/or the second photodefinable material 138-2 of the assembly330 may be deposited on the top surface of the dielectric material139/conductive contacts 146 by lamination, spin coating, or anothersuitable technique.

FIG. 27B illustrates an assembly 332 subsequent to exposing the assembly330 (FIG. 27A) to a source of patterned illumination to cause thephotodefinable materials 138 to selectively cross-link in accordancewith the pattern of the illumination, and then providing a developersolution to selectively remove portions of the photodefinable materials138, leaving openings 165 that expose the conductive contacts 146. Inparticular, FIG. 27B illustrates an illumination pattern 159 in whichthe white portions represent a high dose of illumination, the blackportions represent a low or zero dose of illumination, and the grayportions illustrate an intermediate dose of illumination. Theillumination pattern 159 of FIG. 27B is a “gray-scale mask,” includinghigh, low, and intermediate levels of illumination; such masks may bemore complex than masks with only high and low illumination levels, butmay eliminate or reduce the need for multiple masks and thereby improvefeature alignment. The photodefinable materials 138 in the assembly 332are negative tone; exposure to illumination causes the exposed portionsof the photodefinable materials 138 to “harden” such that the unexposedportions of the photodefinable materials 138 may be etched away by thedeveloper solution. In other embodiments, positive tone photodefinablematerials 138 may be used; in such embodiments, the illumination pattern159 may be inverted. In the embodiment of FIG. 27B, the secondphotodefinable material 138-2 (e.g., a solder resist) may be cured by ahigh dose of illumination, while the first photodefinable material 138-1may be cured by a low dose of illumination. In various embodiments, thesame developer solution (or different developer solutions) may be usedto develop the first photodefinable material 138-1 and the secondphotodefinable material 138-2.

FIG. 27C illustrates an assembly 333 subsequent to providing solder inthe openings 165 of the assembly 332 (FIG. 27B) to form the DTPSinterconnects 150. Any suitable technique may be used to form the DTPSinterconnects 150 (e.g., any suitable solder bump, solder microball, orsolder plating technique). In some embodiments, the DTPS interconnects150-1 and the DTPS interconnects 150-2 may be formed substantiallysimultaneously, while in other embodiments, the DTPS interconnects 150-1and the DTPS interconnects 150-2 may be formed in different operations.

FIG. 27B illustrates an embodiment in which the first photodefinablematerial 138-1 and the second photodefinable material 138-2 aresimultaneously illuminated and developed. In other embodiments, thesecond photodefinable material 138-2 may be illuminated and developedfirst, and the first photodefinable material 138 1 may be subsequentlyilluminated and developed. For example, FIG. 27D illustrates an assembly334 subsequent to illuminating and developing the second photodefinablematerial 138-2 of the assembly 330 (FIG. 27A) without patterning thefirst photodefinable material 138-1. In the embodiment of FIG. 27D, thesecond photodefinable material 138-2 may be a negative tone material, asreflected by the accompanying illumination pattern 159. FIG. 27D alsoillustrates the potential for a “misalignment” of the illuminationpattern 159 with the underlying pattern of conductive contacts 146.

FIG. 27E illustrates an assembly 335 subsequent to illuminating indeveloping the first photodefinable material 138-1 of the assembly 334(FIG. 27D). In the embodiment of FIG. 27E, the first photodefinablematerial 138-1 may be a positive tone material, as reflected by theaccompanying illumination pattern 159. Patterning the firstphotodefinable material 138-1 and the second photodefinable material138-2 in different operations may increase the risk of misalignmentbetween the patterned first photodefinable material 138-1, the patternedsecond photodefinable material 138-2, and the underlying pattern ofconductive contacts 146. For example, in some embodiments, since thepatterning of the second photodefinable material 138-2 may define thesidewalls 142 of the recess 108, a misalignment of the patterning of thesecond photodefinable material 138-2 may result in the conductivecontacts 146-1 not being centered in the recess 108, or in an otherwisedetectable offset 167 between the patterned first photodefinablematerial 138-1, the patterned second photodefinable material 138-2,and/or the underlying pattern of conductive contacts 146. In someembodiments, the offset 167 may be between 1 micron and 10 microns(e.g., between 5 microns and 9 microns). In some embodiments of theassembly 335, the different photodefinable materials 138 may besensitive (e.g., curable or soluble) to electromagnetic energies ofdifferent wavelengths. For example, the first photodefinable material138-1 may be sensitive to I-line light (e.g., with a wavelength of 365nanometers) and the second photodefinable material 138-2 may besensitive to H-line light (e.g., with a wavelength of 405 nanometers).

In some embodiments, a package substrate 102 may include a recess 108formed in a dielectric material 169 at the top surface of the dielectricmaterial 139 and the sidewalls 142 of the recess 108 may be scalloped.For example, FIGS. 28A-28B are side, cross-sectional views of such apackage substrate 102 that may be included in a microelectronic assembly100, in accordance with various embodiments. In particular, FIG. 28B isa detailed view of the area inside the dotted circle of FIG. 28A. in theembodiment of FIG. 28, a single dielectric material 169 may be disposedon the dielectric material 139/conductive contacts 146, and thedielectric material 169 may be patterned with openings to expose theconductive contacts 146; solder or other conductive material may bedisposed in the openings to provide the DTPS interconnects 150, asdiscussed above with reference to FIG. 25 and FIG. 27C. As illustratedin FIG. 28B, the sidewalls 142 of the recess 108 may include indentedscallops 157. The dimensions of the scallops 157 may be between 100nanometers and 10 microns (e.g., between 100 nanometers and 10 microns);as discussed below, these dimensions may depend on the size of thefiller particles (e.g., silica particles) in the dielectric material169. The dielectric material 169 may be a photodefinable material (e.g.,any of the photodefinable materials 138 discussed above) or may not be aphotodefinable material. In some embodiments, the dielectric material169 may include any of the insulating materials for package substrates102 disclosed herein. For example, in some embodiments, the dielectricmaterial 169 may be a build-up film. Although the sidewalls 142 of FIG.28 are shown as substantially perpendicular, in some embodiments, thesidewalls 142 may be overcut (e.g., as discussed above with reference toFIG. 24).

FIGS. 29A-29D are side, cross-sectional views of various stages in anexample process for manufacturing the package substrate 102 of FIG. 28,in accordance with various embodiments.

FIG. 29A illustrates an assembly 336 including a dielectric material 139having conductive contacts 146-1 and 146-2 disposed at its top surface(and conductive contacts 140 disposed at its bottom surface, asdiscussed above), a layer of the dielectric material 169 on thedielectric material 139/conductive contacts 146, a layer of a firstresist material 145-1 on the dielectric material 169, and a layer of asecond resist material 145-2 on the first resist material 145-1. Theresist materials 145 may include any suitable removable resistmaterials, such as dry film resist or liquid photoresist materials.

FIG. 29B illustrates an assembly 338 subsequent to exposing the assembly336 (FIG. 29A) to a source of patterned illumination to cause the resistmaterials 145 to selectively cross-link in accordance with the patternof the illumination, and then providing a developer solution toselectively remove portions of the resist materials 145. The resistmaterials 145 in the assembly 338 are negative tone; in otherembodiments, positive tone resist materials 145 may be used (and theillumination pattern 159 may be inverted).

FIG. 29C illustrates an assembly 340 subsequent to directionally etchingthe dielectric material 169 of the assembly 338 (FIG. 29B) in accordancewith the pattern of the patterned resist materials 145, then removingany remaining resist materials 145. The directional etching of thedielectric material 169 may “transfer” the pattern of the patternedresist materials 145 into the dielectric material 169, creating openings165 in the dielectric material 169 that expose the conductive contacts146. In some embodiments, the directional etch of the dielectricmaterial 169 may be a dry etch process. In some embodiments, thedirectional etch of the dielectric material 169 may be performed byreactive ion etching (e.g., inductively coupled plasma reactive ionetching).

FIG. 29D is a detailed view of the area inside the dotted circle of FIG.29C. In some embodiments, the etching of the dielectric material 169 mayresult in the formation of scallops 157 in the sidewalls 142 of therecess 108. The scallops 157 may result from the removal of fillerparticles (e.g., silica particles) of the dielectric material 169exposed at the sidewalls 142 by the etch. The dimensions of the scallops157 may therefore be a function of the size of the filler particles; insome embodiments, the depth of at least some of the scallops 157 may beless than or equal to the diameter of the filler particles in thedielectric material 169. The assembly 340 may be further processed byproviding solder in the openings 165 (e.g., as discussed above withreference to FIG. 27C).

The package substrates 102 disclosed herein may be included in anysuitable microelectronic assembly 100. FIG. 30 is a side,cross-sectional view of an example microelectronic assembly 100including the package substrate 102 of FIG. 22, in accordance withvarious embodiments. In FIG. 30, the package substrate 102 includesmultiple recesses 108 (formed in accordance with any of the techniquesdisclosed herein); two dies 114-1 are shown as disposed in one of therecesses 108, one die 114-1 is shown is disposed in another of therecesses 108, and the dies 114-1 are coupled to conductive contacts146-1 of the package substrate 102 by DTPS interconnects 150-1. Themicroelectronic assembly 100 of FIG. 30 further includes a die 114-2acting as a “superposer,” extending above and electrically coupled toall of the dies 114-1 via DTD interconnects 130, as well as coupled tothe conductive contacts 146-2 of the package substrate 102 by DTPSinterconnects 150-2.

Although various ones of the accompanying drawings illustrate similarfirst-level interconnect structures within the recess 108 and outsidethe recess 108 (e.g., including the conductive contacts 146-1 and146-2), in some embodiments, first-level interconnect structures insideand outside a recess 108 may be different. For example, in someembodiments, the conductive contacts 146-2 (e.g., a coarse pitch bumpfield) may be solder pads having solder therein that may be mated tocopper pillars (e.g., with added solder balls) on a die 114, and theconductive contacts 146-2 (e.g., a fine pitch field) may be metal padsmated to copper pillars (e.g., with added solder balls) of a die 114 (orvice versa). Solder pads may include copper, and in some embodiments,the copper may be covered with a surface finish (e.g., a metal stackincluding nickel and gold, or a metal stack including palladium, nickel,and gold).

The microelectronic assemblies 100 disclosed herein may be used for anysuitable application. For example, in some embodiments, amicroelectronic assembly 100 may be used to provide an ultra-highdensity and high bandwidth interconnect for field programmable gatearray (FPGA) transceivers and III-V amplifiers. For example, the die114-1 may include FPGA transceiver circuitry or III-V amplifiers, andthe die 114-2 may include FPGA logic. Communications between the die114-1 and the die 114-2 may experience less delay than if suchcommunications were routed through an intermediate device (e.g., aseparate silicon bridge). In some embodiments, the pitch of the DTDinterconnects 130-1 between the die 114-1 and the die 114-2 may be lessthan 100 microns (e.g., between 25 microns and 55 microns) and the pitchof the DTPS interconnects 150-2 between the die 114-2 and the packagesubstrate 102 may be greater than 80 microns (e.g., between 100 micronsand 150 microns). Such applications may be particularly suitable formilitary electronics, 5G wireless communications, WiGig communications,and/or millimeter wave communications.

More generally, the microelectronic assemblies 100 disclosed herein mayallow “blocks” of different kinds of functional circuits to bedistributed into different ones of the dies 114, instead of having allof the circuits included in a single large die, per some conventionalapproaches. In some such conventional approaches, a single large diewould include all of these different circuits to achieve high bandwidth,low loss communication between the circuits, and some or all of thesecircuits may be selectively disabled to adjust the capabilities of thelarge die. However, because the DTD interconnects 130 of themicroelectronic assemblies 100 may allow high bandwidth, low losscommunication between different ones of the dies 114, different circuitsmay be distributed into different dies 114, reducing the total cost ofmanufacture, improving yield, and increasing design flexibility byallowing different dies 114 (e.g., dies 114 formed using differentfabrication technologies) to be readily swapped to achieve differentfunctionality. Additionally, a die 114 stacked on top of another die 114may be closer to the heat spreader 131 than if the circuitry of the twodies were combined into a single die farther from the heat spreader 131,improving thermal performance.

In another example, a die 114-1 that includes active circuitry in amicroelectronic assembly 100 may be used to provide an “active” bridgebetween other dies 114 (e.g., between the dies 114-2 and 114-3, orbetween multiple different dies 114-2, in various embodiments). In somesuch embodiments, power delivery may be provided to the “bottoms” of thedie 114-1 and the other dies 114 through the package substrate 102without requiring additional layers of package substrate 102 above thedie 114-1 through which to route power.

In another example, the die 114-1 in a microelectronic assembly 100 maybe a processing device (e.g., a central processing unit, a graphicsprocessing unit, a FPGA, a modem, an applications processor, etc.), andthe die 114-2 may include high bandwidth memory, transceiver circuitry,and/or input/output circuitry (e.g., Double Data Rate transfercircuitry, Peripheral Component Interconnect Express circuitry, etc.).In some embodiments, the die 114-1 may include a set of conductivecontacts 124 to interface with a high bandwidth memory die 114-2, adifferent set of conductive contacts 124 to interface with aninput/output circuitry die 114-2, etc. The particular high bandwidthmemory die 114-2, input/output circuitry die 114-2, etc. may be selectedfor the application at hand.

In another example, the die 114-1 in a microelectronic assembly 100 maybe a cache memory (e.g., a third level cache memory), and one or moredies 114-2 may be processing devices (e.g., a central processing unit, agraphics processing unit, a FPGA, a modem, an applications processor,etc.) that share the cache memory of the die 114-1.

The microelectronic assemblies 100 disclosed herein may be included inany suitable electronic component. FIGS. 31-34 illustrate variousexamples of apparatuses that may include, or be included in, any of themicroelectronic assemblies 100 disclosed herein.

FIG. 31 is a top view of a wafer 1500 and dies 1502 that may be includedin any of the microelectronic assemblies 100 disclosed herein (e.g., asany suitable ones of the dies 114). The wafer 1500 may be composed ofsemiconductor material and may include one or more dies 1502 having ICstructures formed on a surface of the wafer 1500. Each of the dies 1502may be a repeating unit of a semiconductor product that includes anysuitable IC. After the fabrication of the semiconductor product iscomplete, the wafer 1500 may undergo a singulation process in which thedies 1502 are separated from one another to provide discrete “chips” ofthe semiconductor product. The die 1502 may be any of the dies 114disclosed herein. The die 1502 may include one or more transistors(e.g., some of the transistors 1640 of FIG. 32, discussed below),supporting circuitry to route electrical signals to the transistors,passive components (e.g., signal traces, resistors, capacitors, orinductors), and/or any other IC components. In some embodiments, thewafer 1500 or the die 1502 may include a memory device (e.g., a randomaccess memory (RAM) device, such as a static RAM (SRAM) device, amagnetic RAM (MRAM) device, a resistive RAM (RRAM) device, aconductive-bridging RAM (CBRAM) device, etc.), a logic device (e.g., anAND, OR, NAND, or NOR gate), or any other suitable circuit element.Multiple ones of these devices may be combined on a single die 1502. Forexample, a memory array formed by multiple memory devices may be formedon a same die 1502 as a processing device (e.g., the processing device1802 of FIG. 34) or other logic that is configured to store informationin the memory devices or execute instructions stored in the memoryarray. Various ones of the microelectronic assemblies 100 disclosedherein may be manufactured using a die-to-wafer assembly technique inwhich some dies 114 are attached to a wafer 1500 that include others ofthe dies 114, and the wafer 1500 is subsequently singulated.

FIG. 32 is a side, cross-sectional view of an IC device 1600 that may beincluded in any of the microelectronic assemblies 100 disclosed herein(e.g., in any of the dies 114). One or more of the IC devices 1600 maybe included in one or more dies 1502 (FIG. 31). The IC device 1600 maybe formed on a die substrate 1602 (e.g., the wafer 1500 of FIG. 31) andmay be included in a die (e.g., the die 1502 of FIG. 31). The diesubstrate 1602 may be a semiconductor substrate composed ofsemiconductor material systems including, for example, n-type or p-typematerials systems (or a combination of both). The die substrate 1602 mayinclude, for example, a crystalline substrate formed using a bulksilicon or a silicon-on-insulator (SOI) substructure. In someembodiments, the die substrate 1602 may be formed using alternativematerials, which may or may not be combined with silicon, that include,but are not limited to, germanium, indium antimonide, lead telluride,indium arsenide, indium phosphide, gallium arsenide, or galliumantimonide. Further materials classified as group II-VI, III-V, or IVmay also be used to form the die substrate 1602. Although a few examplesof materials from which the die substrate 1602 may be formed aredescribed here, any material that may serve as a foundation for an ICdevice 1600 may be used. The die substrate 1602 may be part of asingulated die (e.g., the dies 1502 of FIG. 31) or a wafer (e.g., thewafer 1500 of FIG. 31).

The IC device 1600 may include one or more device layers 1604 disposedon the die substrate 1602. The device layer 1604 may include features ofone or more transistors 1640 (e.g., metal oxide semiconductorfield-effect transistors (MOSFETs)) formed on the die substrate 1602.The device layer 1604 may include, for example, one or more sourceand/or drain (S/D) regions 1620, a gate 1622 to control current flow inthe transistors 1640 between the S/D regions 1620, and one or more S/Dcontacts 1624 to route electrical signals to/from the S/D regions 1620.The transistors 1640 may include additional features not depicted forthe sake of clarity, such as device isolation regions, gate contacts,and the like. The transistors 1640 are not limited to the type andconfiguration depicted in FIG. 32 and may include a wide variety ofother types and configurations such as, for example, planar transistors,non-planar transistors, or a combination of both. Non-planar transistorsmay include FinFET transistors, such as double-gate transistors ortri-gate transistors, and wrap-around or all-around gate transistors,such as nanoribbon and nanowire transistors.

Each transistor 1640 may include a gate 1622 formed of at least twolayers, a gate dielectric and a gate electrode. The gate dielectric mayinclude one layer or a stack of layers. The one or more layers mayinclude silicon oxide, silicon dioxide, silicon carbide, and/or a high-kdielectric material. The high-k dielectric material may include elementssuch as hafnium, silicon, oxygen, titanium, tantalum, lanthanum,aluminum, zirconium, barium, strontium, yttrium, lead, scandium,niobium, and zinc. Examples of high-k materials that may be used in thegate dielectric include, but are not limited to, hafnium oxide, hafniumsilicon oxide, lanthanum oxide, lanthanum aluminum oxide, zirconiumoxide, zirconium silicon oxide, tantalum oxide, titanium oxide, bariumstrontium titanium oxide, barium titanium oxide, strontium titaniumoxide, yttrium oxide, aluminum oxide, lead scandium tantalum oxide, andlead zinc niobate. In some embodiments, an annealing process may becarried out on the gate dielectric to improve its quality when a high-kmaterial is used.

The gate electrode may be formed on the gate dielectric and may includeat least one p-type work function metal or n-type work function metal,depending on whether the transistor 1640 is to be a p-type metal oxidesemiconductor (PMOS) or an n-type metal oxide semiconductor (NMOS)transistor. In some implementations, the gate electrode may consist of astack of two or more metal layers, where one or more metal layers arework function metal layers and at least one metal layer is a fill metallayer. Further metal layers may be included for other purposes, such asa barrier layer. For a PMOS transistor, metals that may be used for thegate electrode include, but are not limited to, ruthenium, palladium,platinum, cobalt, nickel, conductive metal oxides (e.g., rutheniumoxide), and any of the metals discussed below with reference to an NMOStransistor (e.g., for work function tuning). For an NMOS transistor,metals that may be used for the gate electrode include, but are notlimited to, hafnium, zirconium, titanium, tantalum, aluminum, alloys ofthese metals, carbides of these metals (e.g., hafnium carbide, zirconiumcarbide, titanium carbide, tantalum carbide, and aluminum carbide), andany of the metals discussed above with reference to a PMOS transistor(e.g., for work function tuning).

In some embodiments, when viewed as a cross-section of the transistor1640 along the source-channel-drain direction, the gate electrode mayconsist of a U-shaped structure that includes a bottom portionsubstantially parallel to the surface of the die substrate 1602 and twosidewall portions that are substantially perpendicular to the topsurface of the die substrate 1602. In other embodiments, at least one ofthe metal layers that form the gate electrode may simply be a planarlayer that is substantially parallel to the top surface of the diesubstrate 1602 and does not include sidewall portions substantiallyperpendicular to the top surface of the die substrate 1602. In otherembodiments, the gate electrode may consist of a combination of U-shapedstructures and planar, non-U-shaped structures. For example, the gateelectrode may consist of one or more U-shaped metal layers formed atopone or more planar, non-U-shaped layers.

In some embodiments, a pair of sidewall spacers may be formed onopposing sides of the gate stack to bracket the gate stack. The sidewallspacers may be formed from materials such as silicon nitride, siliconoxide, silicon carbide, silicon nitride doped with carbon, and siliconoxynitride. Processes for forming sidewall spacers are well known in theart and generally include deposition and etching process steps. In someembodiments, a plurality of spacer pairs may be used; for instance, twopairs, three pairs, or four pairs of sidewall spacers may be formed onopposing sides of the gate stack.

The S/D regions 1620 may be formed within the die substrate 1602adjacent to the gate 1622 of each transistor 1640. The S/D regions 1620may be formed using an implantation/diffusion process or anetching/deposition process, for example. In the former process, dopantssuch as boron, aluminum, antimony, phosphorous, or arsenic may beion-implanted into the die substrate 1602 to form the S/D regions 1620.An annealing process that activates the dopants and causes them todiffuse farther into the die substrate 1602 may follow theion-implantation process. In the latter process, the die substrate 1602may first be etched to form recesses at the locations of the S/D regions1620. An epitaxial deposition process may then be carried out to fillthe recesses with material that is used to fabricate the S/D regions1620. In some implementations, the S/D regions 1620 may be fabricatedusing a silicon alloy such as silicon germanium or silicon carbide. Insome embodiments, the epitaxially deposited silicon alloy may be dopedin situ with dopants such as boron, arsenic, or phosphorous. In someembodiments, the S/D regions 1620 may be formed using one or morealternate semiconductor materials such as germanium or a group III-Vmaterial or alloy. In further embodiments, one or more layers of metaland/or metal alloys may be used to form the S/D regions 1620.

Electrical signals, such as power and/or input/output (I/O) signals, maybe routed to and/or from the devices (e.g., transistors 1640) of thedevice layer 1604 through one or more interconnect layers disposed onthe device layer 1604 (illustrated in FIG. 32 as interconnect layers1606-1610). For example, electrically conductive features of the devicelayer 1604 (e.g., the gate 1622 and the S/D contacts 1624) may beelectrically coupled with the interconnect structures 1628 of theinterconnect layers 1606-1610. The one or more interconnect layers1606-1610 may form a metallization stack (also referred to as an “ILDstack”) 1619 of the IC device 1600.

The interconnect structures 1628 may be arranged within the interconnectlayers 1606-1610 to route electrical signals according to a wide varietyof designs; in particular, the arrangement is not limited to theparticular configuration of interconnect structures 1628 depicted inFIG. 32. Although a particular number of interconnect layers 1606-1610is depicted in FIG. 32, embodiments of the present disclosure include ICdevices having more or fewer interconnect layers than depicted.

In some embodiments, the interconnect structures 1628 may include lines1628 a and/or vias 1628 b filled with an electrically conductivematerial such as a metal. The lines 1628 a may be arranged to routeelectrical signals in a direction of a plane that is substantiallyparallel with a surface of the die substrate 1602 upon which the devicelayer 1604 is formed. For example, the lines 1628 a may route electricalsignals in a direction in and out of the page from the perspective ofFIG. 32. The vias 1628 b may be arranged to route electrical signals ina direction of a plane that is substantially perpendicular to thesurface of the die substrate 1602 upon which the device layer 1604 isformed. In some embodiments, the vias 1628 b may electrically couplelines 1628 a of different interconnect layers 1606-1610 together.

The interconnect layers 1606-1610 may include a dielectric material 1626disposed between the interconnect structures 1628, as shown in FIG. 32.In some embodiments, the dielectric material 1626 disposed between theinterconnect structures 1628 in different ones of the interconnectlayers 1606-1610 may have different compositions; in other embodiments,the composition of the dielectric material 1626 between differentinterconnect layers 1606-1610 may be the same.

A first interconnect layer 1606 (referred to as Metal 1 or “M1”) may beformed directly on the device layer 1604. In some embodiments, the firstinterconnect layer 1606 may include lines 1628 a and/or vias 1628 b, asshown. The lines 1628 a of the first interconnect layer 1606 may becoupled with contacts (e.g., the S/D contacts 1624) of the device layer1604.

A second interconnect layer 1608 (referred to as Metal 2 or “M2”) may beformed directly on the first interconnect layer 1606. In someembodiments, the second interconnect layer 1608 may include vias 1628 bto couple the lines 1628 a of the second interconnect layer 1608 withthe lines 1628 a of the first interconnect layer 1606. Although thelines 1628 a and the vias 1628 b are structurally delineated with a linewithin each interconnect layer (e.g., within the second interconnectlayer 1608) for the sake of clarity, the lines 1628 a and the vias 1628b may be structurally and/or materially contiguous (e.g., simultaneouslyfilled during a dual-damascene process) in some embodiments.

A third interconnect layer 1610 (referred to as Metal 3 or “M3”) (andadditional interconnect layers, as desired) may be formed in successionon the second interconnect layer 1608 according to similar techniquesand configurations described in connection with the second interconnectlayer 1608 or the first interconnect layer 1606. In some embodiments,the interconnect layers that are “higher up” in the metallization stack1619 in the IC device 1600 (i.e., farther away from the device layer1604) may be thicker.

The IC device 1600 may include a solder resist material 1634 (e.g.,polyimide or similar material) and one or more conductive contacts 1636formed on the interconnect layers 1606-1610. In FIG. 32, the conductivecontacts 1636 are illustrated as taking the form of bond pads. Theconductive contacts 1636 may be electrically coupled with theinterconnect structures 1628 and configured to route the electricalsignals of the transistor(s) 1640 to other external devices. Forexample, solder bonds may be formed on the one or more conductivecontacts 1636 to mechanically and/or electrically couple a chipincluding the IC device 1600 with another component (e.g., a circuitboard). The IC device 1600 may include additional or alternatestructures to route the electrical signals from the interconnect layers1606-1610; for example, the conductive contacts 1636 may include otheranalogous features (e.g., posts) that route the electrical signals toexternal components. The conductive contacts 1636 may serve as theconductive contacts 122 or 124, as appropriate.

In some embodiments in which the IC device 1600 is a double-sided die(e.g., like the die 114-1), the IC device 1600 may include anothermetallization stack (not shown) on the opposite side of the devicelayer(s) 1604. This metallization stack may include multipleinterconnect layers as discussed above with reference to theinterconnect layers 1606-1610, to provide conductive pathways (e.g.,including conductive lines and vias) between the device layer(s) 1604and additional conductive contacts (not shown) on the opposite side ofthe IC device 1600 from the conductive contacts 1636. These additionalconductive contacts may serve as the conductive contacts 122 or 124, asappropriate.

In other embodiments in which the IC device 1600 is a double-sided die(e.g., like the die 114-1), the IC device 1600 may include one or moreTSVs through the die substrate 1602; these TSVs may make contact withthe device layer(s) 1604, and may provide conductive pathways betweenthe device layer(s) 1604 and additional conductive contacts (not shown)on the opposite side of the IC device 1600 from the conductive contacts1636. These additional conductive contacts may serve as the conductivecontacts 122 or 124, as appropriate.

FIG. 33 is a side, cross-sectional view of an IC device assembly 1700that may include any of the microelectronic assemblies 100 disclosedherein. In some embodiments, the IC device assembly 1700 may be amicroelectronic assembly 100. The IC device assembly 1700 includes anumber of components disposed on a circuit board 1702 (which may be,e.g., a motherboard). The IC device assembly 1700 includes componentsdisposed on a first surface 1740 of the circuit board 1702 and anopposing second surface 1742 of the circuit board 1702; generally,components may be disposed on one or both faces 1740 and 1742. Any ofthe IC packages discussed below with reference to the IC device assembly1700 may take the form of any suitable ones of the embodiments of themicroelectronic assemblies 100 disclosed herein.

In some embodiments, the circuit board 1702 may be a PCB includingmultiple metal layers separated from one another by layers of dielectricmaterial and interconnected by electrically conductive vias. Any one ormore of the metal layers may be formed in a desired circuit pattern toroute electrical signals (optionally in conjunction with other metallayers) between the components coupled to the circuit board 1702. Inother embodiments, the circuit board 1702 may be a non-PCB substrate. Insome embodiments the circuit board 1702 may be, for example, the circuitboard 133.

The IC device assembly 1700 illustrated in FIG. 33 includes apackage-on-interposer structure 1736 coupled to the first surface 1740of the circuit board 1702 by coupling components 1716. The couplingcomponents 1716 may electrically and mechanically couple thepackage-on-interposer structure 1736 to the circuit board 1702, and mayinclude solder balls (as shown in FIG. 33), male and female portions ofa socket, an adhesive, an underfill material, and/or any other suitableelectrical and/or mechanical coupling structure.

The package-on-interposer structure 1736 may include an IC package 1720coupled to an interposer 1704 by coupling components 1718. The couplingcomponents 1718 may take any suitable form for the application, such asthe forms discussed above with reference to the coupling components1716. Although a single IC package 1720 is shown in FIG. 33, multiple ICpackages may be coupled to the interposer 1704; indeed, additionalinterposers may be coupled to the interposer 1704. The interposer 1704may provide an intervening substrate used to bridge the circuit board1702 and the IC package 1720. The IC package 1720 may be or include, forexample, a die (the die 1502 of FIG. 31), an IC device (e.g., the ICdevice 1600 of FIG. 32), or any other suitable component. Generally, theinterposer 1704 may spread a connection to a wider pitch or reroute aconnection to a different connection. For example, the interposer 1704may couple the IC package 1720 (e.g., a die) to a set of ball grid array(BGA) conductive contacts of the coupling components 1716 for couplingto the circuit board 1702. In the embodiment illustrated in FIG. 33, theIC package 1720 and the circuit board 1702 are attached to opposingsides of the interposer 1704; in other embodiments, the IC package 1720and the circuit board 1702 may be attached to a same side of theinterposer 1704. In some embodiments, three or more components may beinterconnected by way of the interposer 1704.

In some embodiments, the interposer 1704 may be formed as a PCB,including multiple metal layers separated from one another by layers ofdielectric material and interconnected by electrically conductive vias.In some embodiments, the interposer 1704 may be formed of an epoxyresin, a fiberglass-reinforced epoxy resin, an epoxy resin withinorganic fillers, a ceramic material, or a polymer material such aspolyimide. In some embodiments, the interposer 1704 may be formed ofalternate rigid or flexible materials that may include the samematerials described above for use in a semiconductor substrate, such assilicon, germanium, and other group III-V and group IV materials. Theinterposer 1704 may include metal interconnects 1708 and vias 1710,including but not limited to TSVs 1706. The interposer 1704 may furtherinclude embedded devices 1714, including both passive and activedevices. Such devices may include, but are not limited to, capacitors,decoupling capacitors, resistors, inductors, fuses, diodes,transformers, sensors, electrostatic discharge (ESD) devices, and memorydevices. More complex devices such as radio frequency devices, poweramplifiers, power management devices, antennas, arrays, sensors, andmicroelectromechanical systems (MEMS) devices may also be formed on theinterposer 1704. The package-on-interposer structure 1736 may take theform of any of the package-on-interposer structures known in the art.

The IC device assembly 1700 may include an IC package 1724 coupled tothe first surface 1740 of the circuit board 1702 by coupling components1722. The coupling components 1722 may take the form of any of theembodiments discussed above with reference to the coupling components1716, and the IC package 1724 may take the form of any of theembodiments discussed above with reference to the IC package 1720.

The IC device assembly 1700 illustrated in FIG. 33 includes apackage-on-package structure 1734 coupled to the second surface 1742 ofthe circuit board 1702 by coupling components 1728. Thepackage-on-package structure 1734 may include an IC package 1726 and anIC package 1732 coupled together by coupling components 1730 such thatthe IC package 1726 is disposed between the circuit board 1702 and theIC package 1732. The coupling components 1728 and 1730 may take the formof any of the embodiments of the coupling components 1716 discussedabove, and the IC packages 1726 and 1732 may take the form of any of theembodiments of the IC package 1720 discussed above. Thepackage-on-package structure 1734 may be configured in accordance withany of the package-on-package structures known in the art.

FIG. 34 is a block diagram of an example electrical device 1800 that mayinclude one or more of the microelectronic assemblies 100 disclosedherein. For example, any suitable ones of the components of theelectrical device 1800 may include one or more of the IC deviceassemblies 1700, IC devices 1600, or dies 1502 disclosed herein, and maybe arranged in any of the microelectronic assemblies 100 disclosedherein. A number of components are illustrated in FIG. 34 as included inthe electrical device 1800, but any one or more of these components maybe omitted or duplicated, as suitable for the application. In someembodiments, some or all of the components included in the electricaldevice 1800 may be attached to one or more motherboards. In someembodiments, some or all of these components are fabricated onto asingle system-on-a-chip (SoC) die.

Additionally, in various embodiments, the electrical device 1800 may notinclude one or more of the components illustrated in FIG. 34, but theelectrical device 1800 may include interface circuitry for coupling tothe one or more components. For example, the electrical device 1800 maynot include a display device 1806, but may include display deviceinterface circuitry (e.g., a connector and driver circuitry) to which adisplay device 1806 may be coupled. In another set of examples, theelectrical device 1800 may not include an audio input device 1824 or anaudio output device 1808, but may include audio input or output deviceinterface circuitry (e.g., connectors and supporting circuitry) to whichan audio input device 1824 or audio output device 1808 may be coupled.

The electrical device 1800 may include a processing device 1802 (e.g.,one or more processing devices). As used herein, the term “processingdevice” or “processor” may refer to any device or portion of a devicethat processes electronic data from registers and/or memory to transformthat electronic data into other electronic data that may be stored inregisters and/or memory. The processing device 1802 may include one ormore digital signal processors (DSPs), application-specific integratedcircuits (ASICs), central processing units (CPUs), graphics processingunits (GPUs), cryptoprocessors (specialized processors that executecryptographic algorithms within hardware), server processors, or anyother suitable processing devices. The electrical device 1800 mayinclude a memory 1804, which may itself include one or more memorydevices such as volatile memory (e.g., dynamic random access memory(DRAM)), nonvolatile memory (e.g., read-only memory (ROM)), flashmemory, solid state memory, and/or a hard drive. In some embodiments,the memory 1804 may include memory that shares a die with the processingdevice 1802. This memory may be used as cache memory and may includeembedded dynamic random access memory (eDRAM) or spin transfer torquemagnetic random access memory (STT-MRAM).

In some embodiments, the electrical device 1800 may include acommunication chip 1812 (e.g., one or more communication chips). Forexample, the communication chip 1812 may be configured for managingwireless communications for the transfer of data to and from theelectrical device 1800. The term “wireless” and its derivatives may beused to describe circuits, devices, systems, methods, techniques,communications channels, etc., that may communicate data through the useof modulated electromagnetic radiation through a nonsolid medium. Theterm does not imply that the associated devices do not contain anywires, although in some embodiments they might not.

The communication chip 1812 may implement any of a number of wirelessstandards or protocols, including but not limited to Institute forElectrical and Electronic Engineers (IEEE) standards including Wi-Fi(IEEE 802.11 family), IEEE 802.16 standards (e.g., IEEE 802.16-2005Amendment), Long-Term Evolution (LTE) project along with any amendments,updates, and/or revisions (e.g., advanced LTE project, ultra mobilebroadband (UMB) project (also referred to as “3GPP2”), etc.). IEEE802.16 compatible Broadband Wireless Access (BWA) networks are generallyreferred to as WiMAX networks, an acronym that stands for WorldwideInteroperability for Microwave Access, which is a certification mark forproducts that pass conformity and interoperability tests for the IEEE802.16 standards. The communication chip 1812 may operate in accordancewith a Global System for Mobile Communication (GSM), General PacketRadio Service (GPRS), Universal Mobile Telecommunications System (UMTS),High Speed Packet Access (HSPA), Evolved HSPA (E-HSPA), or LTE network.The communication chip 1812 may operate in accordance with Enhanced Datafor GSM Evolution (EDGE), GSM EDGE Radio Access Network (GERAN),Universal Terrestrial Radio Access Network (UTRAN), or Evolved UTRAN(E-UTRAN). The communication chip 1812 may operate in accordance withCode Division Multiple Access (CDMA), Time Division Multiple Access(TDMA), Digital Enhanced Cordless Telecommunications (DECT),Evolution-Data Optimized (EV-DO), and derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The communication chip 1812 may operate in accordance with otherwireless protocols in other embodiments. The electrical device 1800 mayinclude an antenna 1822 to facilitate wireless communications and/or toreceive other wireless communications (such as AM or FM radiotransmissions).

In some embodiments, the communication chip 1812 may manage wiredcommunications, such as electrical, optical, or any other suitablecommunication protocols (e.g., the Ethernet). As noted above, thecommunication chip 1812 may include multiple communication chips. Forinstance, a first communication chip 1812 may be dedicated toshorter-range wireless communications such as Wi-Fi or Bluetooth, and asecond communication chip 1812 may be dedicated to longer-range wirelesscommunications such as global positioning system (GPS), EDGE, GPRS,CDMA, WiMAX, LTE, EV-DO, or others. In some embodiments, a firstcommunication chip 1812 may be dedicated to wireless communications, anda second communication chip 1812 may be dedicated to wiredcommunications.

The electrical device 1800 may include battery/power circuitry 1814. Thebattery/power circuitry 1814 may include one or more energy storagedevices (e.g., batteries or capacitors) and/or circuitry for couplingcomponents of the electrical device 1800 to an energy source separatefrom the electrical device 1800 (e.g., AC line power).

The electrical device 1800 may include a display device 1806 (orcorresponding interface circuitry, as discussed above). The displaydevice 1806 may include any visual indicators, such as a heads-updisplay, a computer monitor, a projector, a touchscreen display, aliquid crystal display (LCD), a light-emitting diode display, or a flatpanel display.

The electrical device 1800 may include an audio output device 1808 (orcorresponding interface circuitry, as discussed above). The audio outputdevice 1808 may include any device that generates an audible indicator,such as speakers, headsets, or earbuds.

The electrical device 1800 may include an audio input device 1824 (orcorresponding interface circuitry, as discussed above). The audio inputdevice 1824 may include any device that generates a signalrepresentative of a sound, such as microphones, microphone arrays, ordigital instruments (e.g., instruments having a musical instrumentdigital interface (MIDI) output).

The electrical device 1800 may include a GPS device 1818 (orcorresponding interface circuitry, as discussed above). The GPS device1818 may be in communication with a satellite-based system and mayreceive a location of the electrical device 1800, as known in the art.

The electrical device 1800 may include an other output device 1810 (orcorresponding interface circuitry, as discussed above). Examples of theother output device 1810 may include an audio codec, a video codec, aprinter, a wired or wireless transmitter for providing information toother devices, or an additional storage device.

The electrical device 1800 may include an other input device 1820 (orcorresponding interface circuitry, as discussed above). Examples of theother input device 1820 may include an accelerometer, a gyroscope, acompass, an image capture device, a keyboard, a cursor control devicesuch as a mouse, a stylus, a touchpad, a bar code reader, a QuickResponse (QR) code reader, any sensor, or a radio frequencyidentification (RFID) reader.

The electrical device 1800 may have any desired form factor, such as ahandheld or mobile electrical device (e.g., a cell phone, a smart phone,a mobile internet device, a music player, a tablet computer, a laptopcomputer, a netbook computer, an ultrabook computer, a personal digitalassistant (PDA), an ultra mobile personal computer, etc.), a desktopelectrical device, a server or other networked computing component, aprinter, a scanner, a monitor, a set-top box, an entertainment controlunit, a vehicle control unit, a digital camera, a digital videorecorder, or a wearable electrical device. In some embodiments, theelectrical device 1800 may be any other electronic device that processesdata.

The following paragraphs provide various examples of the embodimentsdisclosed herein.

Example 1 is a microelectronic assembly, including: a package substrateincluding a dielectric material having a first surface and an opposingsecond surface, a first photodefinable material on at least a portion ofthe second surface, and a second photodefinable material on at least aportion of the first photodefinable material, wherein the secondphotodefinable material has a different material composition than thefirst photodefinable material.

Example 2 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes a solder resist.

Example 3 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes a photoimageable dielectric.

Example 4 may include the subject matter of any of Examples 1-3, and mayfurther specify that one of the first photodefinable material or thesecond photodefinable material has a negative tone, and an other of thefirst photodefinable material or the second photodefinable material hasa positive tone.

Example 5 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes barium and sulfur.

Example 6 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica.

Example 7 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 8 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 70 percent to 90percent by weight.

Example 9 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material includes silica in anamount of 70 percent to 90 percent by weight, and the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 10 may include the subject matter of Example 1, and may furtherspecify that the first photodefinable material is a solder resist, andthe second photodefinable material is a photoimageable dielectric.

Example 11 may include the subject matter of any of Examples 1-10, andmay further specify that a thickness of the first photodefinablematerial is between 10 microns and 75 microns.

Example 12 may include the subject matter of any of Examples 1-11, andmay further specify that a thickness of the second photodefinablematerial is between 20 microns and 200 microns.

Example 13 may include the subject matter of any of Examples 1-12, andmay further specify that the second photodefinable material provides asidewall of a recess.

Example 14 may include the subject matter of Example 13, and may furtherspecify that the sidewall is undercut.

Example 15 may include the subject matter of Example 13, and may furtherspecify that the sidewall is overcut.

Example 16 may include the subject matter of any of Examples 13-15, andmay further specify that corners of a top view of the recess have arounding radius that is less than 10 microns.

Example 17 may include the subject matter of any of Examples 1-16, andmay further specify that the package substrate further includes firstconductive contacts and second conductive contacts, first openingsthrough the first photodefinable material and the second photodefinablematerial expose the first conductive contacts, and second openingsthrough the first photodefinable material expose the second conductivecontacts.

Example 18 may include the subject matter of Example 17, and may furtherspecify that the first conductive contacts have a pitch that is largerthan a pitch of the second conductive contacts.

Example 19 may include the subject matter of any of Examples 17-18, andmay further include: solder material in the first openings and in thesecond openings.

Example 20 may include the subject matter of any of Examples 17-19, andmay further specify that the second photodefinable material provides asidewall of a recess, and the second openings are offset by a nonzeroamount from being centered in the recess.

Example 21 may include the subject matter of any of Examples 17-20, andmay further include: a first die conductively coupled to at least someof the first conductive contacts; and a second die conductively coupledto the second conductive contacts.

Example 22 may include the subject matter of Example 21, and may furtherspecify that the first die extends at least partially over the seconddie.

Example 23 may include the subject matter of any of Examples 21-22, andmay further specify that the second die has a first surface and anopposing second surface, conductive contacts at the first surface of thesecond die are conductively coupled to the second conductive contacts,and conductive contacts at the second surface of the second die areconductively coupled to conductive contacts of the first die.

Example 24 may include the subject matter of Example 23, and may furtherinclude: a third die conductively coupled to at least some of the firstconductive contacts, wherein conductive contacts at the second surfaceof the second die are conductively coupled to conductive contacts of thethird die.

Example 25 may include the subject matter of any of Examples 17-24, andmay further specify that the first conductive contacts have a pitchbetween 80 microns and 200 microns.

Example 26 may include the subject matter of any of Examples 17-25, andmay further specify that the second conductive contacts have a pitchbetween 20 microns and 80 microns.

Example 27 may include the subject matter of any of Examples 1-26, andmay further specify that the dielectric material includes a build-upfilm.

Example 28 may include the subject matter of any of Examples 1-27, andmay further include: a circuit board coupled to the package substrate;wherein the circuit board is included in a handheld computing device ora server.

Example 29 is a microelectronic assembly, including: a package substratehaving a first surface and an opposing second surface, wherein thepackage substrate includes a dielectric material at the second surface,the dielectric material includes a recess, and sidewalls of the recessare undercut.

Example 30 may include the subject matter of Example 29, and may furtherspecify that the dielectric material is a first dielectric material, thepackage substrate includes a second dielectric material, the seconddielectric material has a first surface and an opposing second surface,and the first dielectric material includes a first photodefinablematerial on at least a portion of the second surface of the seconddielectric material, and a second photodefinable material on at least aportion of the first photodefinable material, wherein the secondphotodefinable material has a different material composition than thefirst photodefinable material.

Example 31 may include the subject matter of Example 30, and may furtherspecify that one of the first photodefinable material or the secondphotodefinable material has a negative tone, and an other of the firstphotodefinable material or the second photodefinable material has apositive tone.

Example 32 may include the subject matter of Example 30, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 33 may include the subject matter of Example 30, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 70 percent to 90percent by weight.

Example 34 may include the subject matter of Example 30, and may furtherspecify that the first photodefinable material includes silica in anamount of 70 percent to 90 percent by weight, and the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 35 may include the subject matter of Example 30, and may furtherspecify that the first photodefinable material is a solder resist, andthe second photodefinable material is a photoimageable dielectric.

Example 36 may include the subject matter of any of Examples 30-34, andmay further specify that a thickness of the first photodefinablematerial is between 10 microns and 75 microns.

Example 37 may include the subject matter of any of Examples 30-36, andmay further specify that a thickness of the second photodefinablematerial is between 20 microns and 200 microns.

Example 38 may include the subject matter of any of Examples 29-37, andmay further specify that the dielectric material includes a solderresist.

Example 39 may include the subject matter of any of Examples 29-37, andmay further specify that the dielectric material includes aphotoimageable dielectric.

Example 40 may include the subject matter of any of Examples 29-37, andmay further specify that the dielectric material includes barium andsulfur.

Example 41 may include the subject matter of any of Examples 29-37, andmay further specify that the dielectric material includes silica.

Example 42 may include the subject matter of any of Examples 29-41, andmay further specify that corners of a top view of the recess have arounding radius that is less than 10 microns.

Example 43 may include the subject matter of any of Examples 29-42, andmay further specify that the package substrate further includes firstconductive contacts and second conductive contacts, first openingsthrough the dielectric material expose the first conductive contacts,and second openings through the dielectric material expose the secondconductive contacts at a bottom of the recess.

Example 44 may include the subject matter of Example 43, and may furtherspecify that the first conductive contacts have a pitch that is largerthan a pitch of the second conductive contacts.

Example 45 may include the subject matter of any of Examples 43-44, andmay further include: solder material in the first openings and in thesecond openings.

Example 46 may include the subject matter of any of Examples 43-45, andmay further specify that the second openings are offset by a nonzeroamount from being centered in the recess.

Example 47 may include the subject matter of any of Examples 43-46, andmay further include: a first die conductively coupled to at least someof the first conductive contacts; and a second die conductively coupledto the second conductive contacts.

Example 48 may include the subject matter of Example 47, and may furtherspecify that the first die extends at least partially over the seconddie.

Example 49 may include the subject matter of any of Examples 47-48, andmay further specify that the second die has a first surface and anopposing second surface, conductive contacts at the first surface of thesecond die are conductively coupled to the second conductive contacts,and conductive contacts at the second surface of the second die areconductively coupled to conductive contacts of the first die.

Example 50 may include the subject matter of any Example 49, and mayfurther include: a third die conductively coupled to at least some ofthe first conductive contacts, wherein conductive contacts at the secondsurface of the second die are conductively coupled to conductivecontacts of the third die.

Example 51 may include the subject matter of any of Examples 43-50, andmay further specify that the first conductive contacts have a pitchbetween 80 microns and 200 microns and the second conductive contactshave a pitch between 20 microns and 80 microns.

Example 52 may include the subject matter of any of Examples 29-51, andmay further include: a circuit board coupled to the package substrate.

Example 53 may include the subject matter of any of Examples 29-52, andmay further specify that the package substrate is included in a handheldcomputing device or a server.

Example 54 is a microelectronic assembly, including: a package substratehaving a first surface and an opposing second surface, wherein thepackage substrate includes a dielectric material at the second surface,the dielectric material includes a recess, and corners of a top view ofthe recess have a rounding radius that is less than 10 microns.

Example 55 may include the subject matter of any of Examples 54, and mayfurther specify that the dielectric material is a first dielectricmaterial, the package substrate includes a second dielectric material,the second dielectric material has a first surface and an opposingsecond surface, and the first dielectric material includes a firstphotodefinable material on at least a portion of the second surface ofthe second dielectric material, and a second photodefinable material onat least a portion of the first photodefinable material, wherein thesecond photodefinable material has a different material composition thanthe first photodefinable material.

Example 56 may include the subject matter of Example 55, and may furtherspecify that one of the first photodefinable material or the secondphotodefinable material has a negative tone, and an other of the firstphotodefinable material or the second photodefinable material has apositive tone.

Example 57 may include the subject matter of Example 55, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 58 may include the subject matter of Example 55, and may furtherspecify that the first photodefinable material or the secondphotodefinable material includes silica in an amount of 70 percent to 90percent by weight.

Example 59 may include the subject matter of Example 55, and may furtherspecify that the first photodefinable material includes silica in anamount of 70 percent to 90 percent by weight, and the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.

Example 60 may include the subject matter of Example 55, and may furtherspecify that the first photodefinable material is a solder resist, andthe second photodefinable material is a photoimageable dielectric.

Example 61 may include the subject matter of any of Examples 55-60, andmay further specify that a thickness of the first photodefinablematerial is between 10 microns and 75 microns.

Example 62 may include the subject matter of any of Examples 55-61, andmay further specify that a thickness of the second photodefinablematerial is between 20 microns and 200 microns.

Example 63 may include the subject matter of Example 54, and may furtherspecify that the dielectric material includes a solder resist.

Example 64 may include the subject matter of Example 54, and may furtherspecify that the dielectric material includes a photoimageabledielectric.

Example 65 may include the subject matter of Example 54, and may furtherspecify that the dielectric material includes barium and sulfur.

Example 66 may include the subject matter of Example 54, and may furtherspecify that the dielectric material includes silica.

Example 67 may include the subject matter of any of Examples 54-66, andmay further specify that sidewalls of the recess are undercut.

Example 68 may include the subject matter of any of Examples 54-67, andmay further specify that the package substrate further includes firstconductive contacts and second conductive contacts, first openingsthrough the dielectric material expose the first conductive contacts,and second openings through the dielectric material expose the secondconductive contacts at a bottom of the recess.

Example 69 may include the subject matter of Example 68, and may furtherspecify that the first conductive contacts have a pitch that is largerthan a pitch of the second conductive contacts.

Example 70 may include the subject matter of any of Examples 68-69, andmay further include: solder material in the first openings and in thesecond openings.

Example 71 may include the subject matter of any of Examples 68-70, andmay further specify that the second openings are offset by a nonzeroamount from being centered in the recess.

Example 72 may include the subject matter of any of Examples 68-71, andmay further include: a first die conductively coupled to at least someof the first conductive contacts; and a second die conductively coupledto the second conductive contacts.

Example 73 may include the subject matter of Example 72, and may furtherspecify that the first die extends at least partially over the seconddie.

Example 74 may include the subject matter of any of Examples 72-73, andmay further specify that the second die has a first surface and anopposing second surface, conductive contacts at the first surface of thesecond die are conductively coupled to the second conductive contacts,and conductive contacts at the second surface of the second die areconductively coupled to conductive contacts of the first die.

Example 75 may include the subject matter of Example 74, and may furtherinclude: a third die conductively coupled to at least some of the firstconductive contacts, wherein conductive contacts at the second surfaceof the second die are conductively coupled to conductive contacts of thethird die.

Example 76 may include the subject matter of any of Examples 68-75, andmay further specify that the first conductive contacts have a pitchbetween 80 microns and 200 microns, and the second conductive contactshave a pitch between 20 microns and 80 microns.

Example 77 may include the subject matter of any of Examples 54-76, andmay further include: a motherboard coupled to the package substrate.

Example 78 may include the subject matter of any of Examples 54-77, andmay further include: wireless communications circuitry.

Example 79 is a microelectronic assembly, including: a package substratehaving a first surface and an opposing second surface, wherein thepackage substrate includes a dielectric material at the second surface,the dielectric material includes a recess, and sidewalls of the recessare scalloped.

Example 80 may include the subject matter of Example 79, and may furtherspecify that the dielectric material is a photodefinable material.

Example 81 may include the subject matter of Example 80, and may furtherspecify that the photodefinable material is on a build-up film layer ofthe package substrate.

Example 82 may include the subject matter of Example 80, and may furtherspecify that the photodefinable material includes silica in an amount of20 percent to 30 percent by weight.

Example 83 may include the subject matter of Example 80, and may furtherspecify that the photodefinable material includes silica in an amount of70 percent to 90 percent by weight.

Example 84 may include the subject matter of Example 80, and may furtherspecify that the photodefinable material is a solder resist.

Example 85 may include the subject matter of Example 80, and may furtherspecify that the photodefinable material is a photoimageable dielectric.

Example 86 may include the subject matter of any of Examples 80-85, andmay further specify that a thickness of the photodefinable material isbetween 20 microns and 300 microns.

Example 87 may include the subject matter of any of Examples 79-86, andmay further specify that a depth of the recess is between 20 microns and200 microns.

Example 88 may include the subject matter of Example 79, and may furtherspecify that the dielectric material includes a solder resist.

Example 89 may include the subject matter of Example 79, and may furtherspecify that the dielectric material includes a photoimageabledielectric.

Example 90 may include the subject matter of Example 79, and may furtherspecify that the dielectric material includes barium and sulfur.

Example 91 may include the subject matter of Example 79, and may furtherspecify that the dielectric material includes silica.

Example 92 may include the subject matter of any of Examples 79-91, andmay further specify that sidewalls of the recess are overcut.

Example 93 may include the subject matter of any of Examples 79-92, andmay further specify that the package substrate further includes firstconductive contacts and second conductive contacts, first openingsthrough the dielectric material expose the first conductive contacts,and second openings through the dielectric material expose the secondconductive contacts at a bottom of the recess.

Example 94 may include the subject matter of Example 93, and may furtherspecify that the first conductive contacts have a pitch that is largerthan a pitch of the second conductive contacts.

Example 95 may include the subject matter of any of Examples 93-94, andmay further include: solder material in the first openings and in thesecond openings.

Example 96 may include the subject matter of any of Examples 93-95, andmay further include: a first die conductively coupled to at least someof the first conductive contacts; and a second die conductively coupledto the second conductive contacts.

Example 97 may include the subject matter of Example 96, and may furtherspecify that the first die extends at least partially over the seconddie.

Example 98 may include the subject matter of any of Examples 96-97, andmay further specify that the second die has a first surface and anopposing second surface, conductive contacts at the first surface of thesecond die are conductively coupled to the second conductive contacts,and conductive contacts at the second surface of the second die areconductively coupled to conductive contacts of the first die.

Example 99 may include the subject matter of Example 98, and may furtherinclude: a third die conductively coupled to at least some of the firstconductive contacts, wherein conductive contacts at the second surfaceof the second die are conductively coupled to conductive contacts of thethird die.

Example 100 may include the subject matter of any of Examples 93-99, andmay further specify that the first conductive contacts have a pitchbetween 80 microns and 200 microns.

Example 101 may include the subject matter of any of Examples 93-100,and may further specify that the second conductive contacts have a pitchbetween 20 microns and 80 microns.

Example 102 may include the subject matter of any of Examples 79-101,and may further specify that the package substrate is a ball grid arraypackage substrate.

Example 103 may include the subject matter of any of Examples 79-102,and may further specify that at least some of the scallops have a depthbetween 100 nanometers and 10 microns.

Example 104 may include the subject matter of any of Examples 79-103,and may further specify that at least some of the scallops have a depthbetween Example 0.1 microns and 10 microns.

Example 105 may include the subject matter of any of Examples 79-104,and may further include: a circuit board coupled to the packagesubstrate.

Example 106 may include the subject matter of any of Examples 79-105,and may further specify that the package substrate is included in ahandheld computing device or a server.

Example 107 is a method of manufacturing a package substrate, including:forming a layer of a first photodefinable material on a surface of apackage substrate assembly, wherein the package substrate assemblyincludes conductive contacts at the surface; forming a layer of a secondphotodefinable material on the first photodefinable material, whereinthe second photodefinable material has a different material compositionfrom the first photodefinable material; and illuminating and developingthe first photodefinable material and the second photodefinable materialto create openings to expose the conductive contacts.

Example 108 may include the subject matter of Example 107, and mayfurther specify that the first photodefinable material and the secondphotodefinable material have opposite tone.

Example 109 may include the subject matter of Example 107, and mayfurther specify that the first photodefinable material and the secondphotodefinable material have a same tone.

Example 110 may include the subject matter of any of Examples 107-108,and may further specify that illuminating and developing the firstphotodefinable material and the second photodefinable material includes:illuminating and developing the second photodefinable material; andafter illuminating and developing the second photodefinable material,illuminating and developing the first photodefinable material.

Example 111 may include the subject matter of any of Examples 107-110,and may further specify that illuminating and developing the firstphotodefinable material and the second photodefinable material includesgray scale masking.

Example 112 may include the subject matter of any of Examples 107-111,and may further specify that the conductive contacts include firstconductive contacts and second conductive contacts, the openings thatexpose the first conductive contacts extend through the firstphotodefinable material and the second photodefinable material, and theopenings that expose the second conductive contacts extend through thefirst photodefinable material.

Example 113 may include the subject matter of Example 112, and mayfurther specify that the second conductive contacts have a smaller pitchthan the first conductive contacts.

Example 114 may include the subject matter of any of Examples 107-113,and may further specify that the first photodefinable material or thesecond photodefinable material includes a solder resist or aphotoimageable dielectric.

Example 115 may include the subject matter of any of Examples 107-114,and may further include: providing solder in the openings.

Example 116 may include the subject matter of any of Examples 107-115,and may further include: electrically coupling one or more dies to theconductive contacts.

Example 117 is a method of manufacturing a package substrate, including:forming a layer of a dielectric material on a surface of a packagesubstrate assembly, wherein the package substrate assembly includesconductive contacts at the surface; forming a layer of a firstphotoresist on the dielectric material; forming a layer of a secondphotoresist on the first photoresist, wherein the second photoresist hasa different material composition from the first photoresist; andilluminating and developing the first photoresist and the secondphotoresist to form a patterned photoresist; and etching the dielectricmaterial in accordance with a pattern of the patterned photoresist tocreate openings to expose the conductive contacts.

Example 118 may include the subject matter of Example 117, and mayfurther include: after etching the dielectric material, removing anyresidual first photoresist or second photoresist.

Example 119 may include the subject matter of any of Examples 117-118,and may further specify that etching the dielectric material includesperforming reactive ion etching.

Example 120 may include the subject matter of any of Examples 117-119,and may further specify that illuminating and developing the firstphotoresist and the second photoresist includes: illuminating anddeveloping the second photoresist; and after illuminating and developingthe second photoresist, illuminating and developing the firstphotoresist.

Example 121 may include the subject matter of any of Examples 117-120,and may further specify that illuminating and developing the firstphotoresist and the second photoresist includes gray scale masking.

Example 122 may include the subject matter of any of Examples 117-121,and may further specify that the conductive contacts include firstconductive contacts and second conductive contacts, the etcheddielectric material includes a recess, and the second conductivecontacts are at a bottom of the recess.

Example 123 may include the subject matter of Example 122, and mayfurther specify that the second conductive contacts have a smaller pitchthan the first conductive contacts.

Example 124 may include the subject matter of any of Examples 117-123,and may further specify that the dielectric material includes a build-upfilm or a photoimageable dielectric.

Example 125 may include the subject matter of any of Examples 117-124,and may further include: providing solder in the openings.

Example 126 may include the subject matter of any of Examples 117-125,and may further include: electrically coupling one or more dies to theconductive contacts.

The invention claimed is:
 1. A microelectronic assembly, comprising: apackage substrate including: a dielectric material having a firstsurface and an opposing second surface, a first photodefinable materialon at least a portion of the second surface, a second photodefinablematerial on at least a portion of the first photodefinable material,wherein the second photodefinable material has a different materialcomposition than the first photodefinable material, and wherein thesecond photodefinable material provides a sidewall of a recess, firstconductive contacts and second conductive contacts, first openingsthrough the first photodefinable material and the second photodefinablematerial exposing the first conductive contacts, and second openingsthrough the first photodefinable material exposing the second conductivecontacts, wherein the second openings are offset by a nonzero amountfrom being centered in the recess.
 2. The microelectronic assembly ofclaim 1, wherein the first conductive contacts have a pitch that islarger than a pitch of the second conductive contacts.
 3. Amicroelectronic assembly, comprising: a package substrate including: adielectric material having a first surface and an opposing secondsurface, a first photodefinable material on at least a portion of thesecond surface, a second photodefinable material on at least a portionof the first photodefinable material, wherein the second photodefinablematerial has a different material composition than the firstphotodefinable material, first conductive contacts and second conductivecontacts, first openings through the first photodefinable material andthe second photodefinable material exposing the first conductivecontacts, and second openings through the first photodefinable materialexposing the second conductive contacts, a first die conductivelycoupled to at least some of the first conductive contacts; and a seconddie conductively coupled to the second conductive contacts, wherein thefirst die extends at least partially over the second die.
 4. Amicroelectronic assembly, comprising: a package substrate including: adielectric material having a first surface and an opposing secondsurface, a first photodefinable material on at least a portion of thesecond surface, a second photodefinable material on at least a portionof the first photodefinable material, wherein the second photodefinablematerial has a different material composition than the firstphotodefinable material, first conductive contacts and second conductivecontacts, first openings through the first photodefinable material andthe second photodefinable material that expose the first conductivecontacts, and second openings through the first photodefinable materialthat expose the second conductive contacts, a first die conductivelycoupled to at least some of the first conductive contacts; and a seconddie conductively coupled to the second conductive contacts, wherein thesecond die has a first surface and an opposing second surface,conductive contacts at the first surface of the second die areconductively coupled to the second conductive contacts, and conductivecontacts at the second surface of the second die are conductivelycoupled to conductive contacts of the first die.
 5. The microelectronicassembly of claim 4, further comprising: a third die conductivelycoupled to at least some of the first conductive contacts, whereinconductive contacts at the second surface of the second die areconductively coupled to conductive contacts of the third die.
 6. Amicroelectronic assembly, comprising: a package substrate having a firstsurface and an opposing second surface, wherein the package substrateincludes: a dielectric material at the second surface, wherein thedielectric material includes a recess, and sidewalls of the recess areundercut, first conductive contacts and second conductive contacts,first openings through the dielectric material exposing the firstconductive contacts, and second openings through the dielectric materialexposing the second conductive contacts at a bottom of the recess, and adie at least partially in the recess and conductively coupled to thesecond conductive contacts.
 7. The microelectronic assembly of claim 6,wherein the first conductive contacts have a pitch between 80 micronsand 200 microns and the second conductive contacts have a pitch between20 microns and 80 microns.
 8. The microelectronic assembly of claim 6,further comprising: a circuit board coupled to the package substrate. 9.The microelectronic assembly of claim 6, wherein the package substrateis included in a handheld computing device or a server.
 10. Amicroelectronic assembly, comprising: a package substrate having a firstsurface and an opposing second surface, wherein the package substrateincludes a dielectric material at the second surface, the dielectricmaterial includes a recess, and corners of a top view of the recess havea rounding radius that is less than 10 microns.
 11. The microelectronicassembly of claim 10, wherein the dielectric material is a firstdielectric material, the package substrate includes a second dielectricmaterial, the second dielectric material has a first surface and anopposing second surface, and the first dielectric material includes: afirst photodefinable material on at least a portion of the secondsurface of the second dielectric material, and a second photodefinablematerial on at least a portion of the first photodefinable material,wherein the second photodefinable material has a different materialcomposition than the first photodefinable material.
 12. Themicroelectronic assembly of claim 10, wherein one of the firstphotodefinable material or the second photodefinable material has anegative tone, and an other of the first photodefinable material or thesecond photodefinable material has a positive tone.
 13. Themicroelectronic assembly of claim 10, wherein the first photodefinablematerial or the second photodefinable material includes silica in anamount of 20 percent to 30 percent by weight.
 14. The microelectronicassembly of claim 10, wherein the first photodefinable material or thesecond photodefinable material includes silica in an amount of 70percent to 90 percent by weight.
 15. The microelectronic assembly ofclaim 1, further comprising: solder material in the first openings andin the second openings.
 16. The microelectronic assembly of claim 1,further comprising: a first die conductively coupled to at least some ofthe first conductive contacts; and a second die conductively coupled tothe second conductive contacts.
 17. The microelectronic assembly ofclaim 10, wherein the first photodefinable material includes silica inan amount of 70 percent to 90 percent by weight, and the secondphotodefinable material includes silica in an amount of 20 percent to 30percent by weight.
 18. The microelectronic assembly of claim 1, whereinthe second die is conductively coupled to the first die bymetal-to-metal interconnects.